Classification of Parietales: 11 Families | Dicotyledonae

In this article we will discuss about the classification of Parietales. According to Engler, Parietales consists of eleven families:-  1. Dilleniaceae 2. Ochnaceae 3. Theaceae 4. Guttiferae 5. Dipterocarpaceae 6. Tamaricaceae 7. Bixaceae 8. Violaceae 9. Flacourtiaceae 10. Passifloraceae 11. Begoniaceae. 

Family # 1. Dilleniaceae:

Dilleniaceae are trees, shrubs, woody climbers or rarely under-shrubs; some are deciduous. Leaves are alternate, rarely opposite, simple, usually with a large blade with prominent and parallel lateral nerves; stipules present or absent. Inflorescence is a cyme or a cymose panicle, or solitary and axillary.

Flowers are regular, usually, pentamerous, bisexual or polygamous or unisexual and dioecious, hypogynous, often large and showy, usually yellow or white, rarely pink.

Sepals 5 or fewer or more, free, imbricate and macrescent spirally arranged. Petals 5 or 2-7, free, imbricate, caducous. Stamens ∞, in one or more whorl, rarely less than 10, free or united at base; filaments often broader above; anthers opening by lateral slits or by apical pores.

Ovary superior of many carpels, fused partially or completely, conduplicately folded; sometimes carpels free or rarely solitary; ovules anatropous, erect, one to many, with ventral raphe on axile placentation or in monocarpellary ovary on marginal placentation; styles curved, as many as carpels; stigma capitate or peltate.

Fruit baccate or follicular. Seeds arillate or not, with crustaceous testa, copious fleshy endosperm and minute embryo.

Acrotrema is a genus of rhizomatous herbs often with pinnately compound leaves. In Pachynema the stem and branches are metamorphosed into phylloclades while the leaves are reduced to scales. In Acrotrema leaves are usually radical. Tetracera has lianas as well as shrubs. In Pachynema the sepals are unequal in size so that the flower is slightly zygomorphic.

In Tetracera empedoclea Gilg there are as many as 15 sepals spirally arranged 911 an elongated thalamus. In Davilla the 2 inner sepals are larger and in some species become woody in fruit. In Hibbertia there are many staminodes surrounding the gynoecium while the few fertile stamens are situated on one side.

Davilla has free stamens; in Acrotrema, Hibbertia stamens are polyadelphous; monadelphous stamens are met with in other genera; anther loculi divergent at base in Tetracera but parallel in other genera, opening by apical pores, e.g., Dillenia bracteata Wight and by slits in other cases. Acrotrema, Tetracera have follicular fruits; in Dillenia the fruit is a baccate pseudocarp.

Floral formula:

Anatomical characters have much in common with families under Ranales. Vessels are solitary with scalariform perforation plates and are scattered in the xylem; the wood parenchyma is apotracheal with thick-walled cells.

Fibres have bordered pits on transverse walls. Anomalous secondary thickening is met with in climbing plants. The stomata are of ranunculaceous type. The floral anatomy is more or less similar to Magnoliaceae and Annonaceae.

The family consists of over 500 species under 18 genera mainly distributed in the tropical countries of the world, a large number being Indo-Malayan. Hibbertia and Pachynema are xerophytes occurring in Australia and a few are found in S. America. In India 10 species are found in the plains and at low elevations in the hills.

Dillenia indica Linn, a medium sized evergreen tree with solitary pendulous flowers about 20 cm. across and fruits of same diametre is common in the southern and eastern parts of India. This is the Chalta-tree fruits of which are acid and are used to make chutney and jam and jelly. This and several other species of Dillenia yield good timber.

The spirocyclic arrangement of the floral parts, free carpels and many stamens point to the primitiveness of the family. The floral anatomy and the anatomy of the stem also speak for its primitiveness. It is similar to Magnoliaceae in some respects and to Theaceae in floral construction.

It is considered that Dilleniaceae has been derived from Magnoliales and has given rise to Theales. Bessey included Dilleniaceae in Ranales but Hutchinson, Takhtajan and Cronquist place it in an order Dilleniales which order is according to them very close to Magnoliales.

Family # 2. Ochnaceae:

Ochnaceae are trees shrubs or undershrub’s, rarely herbs. Leaves are simple, alternate, stipulate, stiff and leathery; stipules caducous. Inflorescence is a terminal panicle or umbel or axillary umbel or fascicle; rarely flower solitary and axillary. Flowers are hermaphrodite, regular, hypogynous, usually bracteate. Receptacle often elongated or expanded in the form of a disc, often enlarged after flowering.

Sepals 5 or 4, rarely 10, free, imbricate, leathery and persistent. Petals 4-10, free, imbricate or contorted, deciduous. Stamens 4-5 or 8-10 or numerous in one or more whorls, inserted on the disc when present, often pushed out on one side; staminodes often present; anthers bilocular, dehiscing by lateral slits longitudinally or by apical pores; filaments often persistent and anthers deciduous.

Ovary superior, of 5-15 free carpels or carpels more or less fused, or united to form a unilocular ovary; ovules many in each locule, erect or pendulous, with ventral raphe; rarely ovules one in each chamber, styles gynobasic; placentation parietal or axile; stigma lobed or capitate. Fruit a capsule or drupe or a cluster of druplets.

Seeds few, rarely numerous or solitary in each druplet; endosperm present or absent, embryo straight or curved.

Some species of Sauvagesia are herbs otherwise plants are shrubs or trees. Godoya splendida Planch, has large pinnate leaves. Sepals are coloured in Ochna. The carpels in Ochna and Ouratea are partly fused but become completely free when mature, have a single ovule in each carpel-chamber and form an aggregate type of fruit. In the African genus Lophira 2 of the persistent sepals enlarge to form the wings of the fruit.

The family consists of about 600 species under 40 genera found in the tropical countries of the world but more in America. Ochna squarrosa Linn, and a few other species of the genus are found in India wild and also in cultivated condition for the beautiful flowers.

The family is allied to Theaceae and Diplerocarpaceae and resembles Guttiferae (Clusiaceae) to some extent. These 3 families are included in the order Theales by Cronquist and Takhtajan while Hutchinson placed Ochnaceae and Dipterocarpaceae in Ochnales and Theaceae in Theales just before Ochnales but included Guttiferae (Clusiaceae) in Guttiferales of another group.

The family is not of much economic importance. Two species of Lophira yield good timber and are known as the African oaks and the seeds of L. alata gives an oil which is the Meni oil of commerce.

Family # 3. Theaceae:

Theaceae are evergreen shrubs or small trees, bark warty or wrinkled, often shedding in flakes Leaves coriaceous, simple, alternate or spirally arranged, exstipulate, secondary veins usually conspicuous underneath.

Inflorescence an axillary cyme rarely terminal panicle, often axillary and solitary; bracts and bracteoles-often gradually pass into sepals and sepals into petals in a Spiro cyclic order; bracteoles persistent or caducuous.

Flowers are actinomorphic, bisexual or polygamous or unisexual and dioecious, hypogynous. Sepals 4-7, usually 5, free or slightly connate at base, imbricate or quincuncial, persisent or caducuous. Petals 4-9, usually 5, free or slightly connate at base, imbricate; the outermost usually smaller.

Stamens usually many rarely few, in one or more whorls, free or connate at base, sometimes in several bundles, often adnate to petals, anthers globose or oblong, versatile or basifixed, dehiscing longitudinally.

Carpels usually 3-5, rarely 2 or 1 or more than 5 and up to 10, fused to form a superior ovary, rarelyperigynous; rarely carpels almost free; cells as many as carpels with 2-8 ovules in each cell, or ovules 1 in each cell, rarely many, pendulous, anatropous, with ventral raphe; placentation axile; styles free or partly connate, often persistent; stigma entire and pointed or lobed.

Fruit baccate or capsular. Seeds rarely arillate; endosperm absent or scanty, granular or oily; embryo straight or curved.

Plants of the genus Asteropeia are climbers, of all other genera are trees or shrubs. In Temstroemia the veins of the leaves are indistinct. In Sladenia the inflorescence is a dichasial cyme; it is an umbellate corymb in Anneslea; while in Eurya and Cleyera flowers are fasciculate. Flowers are unisexual in many species of Laplacea and dioecious in Eurya, polygamous in Temstroemia.

Calyx and corolla are not differentiated in Gordonia and Camellia, gradually passing from bracts to petals in Camellia. In Anneslea calyx is gamosepalous and tubular. In Stewartia there are 6 sepals and 6 petals. The number of stamens vary greatly in different genera. In Eurya sometimes there are only 5 stamens.

In Adinandra 20-100 stamens are found and in Ternstroemia as many as 300 in certain species. Filaments are free or connate at base, monadelphous or polyadelphous; in Gordonia the connate filaments form a cup; in Sladenia dialated below and constricted near apex. In Anneslea ovary is epigynous or perigynous.

In some Ternstroemia ovary is monocarpellary while in Laplacea there may be as many as 10; ovules usually 1-8 in each cell of ovary but in Adinandra often 100 ovules have been found in each cell. The seeds of Sladenia are winged, and the seeds of Schima have foliacious cotyledons.

Sclerides are present in the mesophyll of the leaves as well as in the cortex and pith of young stem. Pallisade layer is one cell thick. Raphides often occur in the ground tissue. The vessels are solitary with scalariform perforation plates. Fibres are bordered pitted. Isolated fibres in the pericycle ultimately unite in a composite mechanical ring. Wood parenchyma is diffuse and usually apotracheal.

The family consists of 23 genera and about 500 species occurring mainly in tropical and subtropical regions of Asia and America. In India it is represented by species in the plains and the hills at lower elevations including the famous tea-plants Camellia sinensis (L.) O. Kuntze and C. assamica Wt. India, Srilanka and E. Africa are the most important countries for tea-production.

Besides the above 2 species of Camellia, C. oleifera Abel and C. sasansqua Thunb. yield the tea-oil from the seeds. C. japonica Linn, is a favourite garden-plant having large showy flowers and dark green glossy leaves.

Seeds of Pyrenaria diospyricarpa Kurz. forms a lather in water and is used as a subs­titute for soap. Schima wallichii Bloemb. and other species of Schima are good timber trees. The leaves of Haploclathra paniculata Benth. are used as tea of inferior quality.

Theaceae resembles Dilleniaceae in floral morphology to some extent as well as in anatomy of the stem. It has also much in common with Guttiferae (Clusiaceae) and Marcgraviaceae and to some extent with Dipterocarpaceae, Ochnaceae, Actinidiaceae and Caryocaraceae. It is presumed that Theaceae has been derived from Dilleniaceae directly or through some allied families.

Family # 4. Guttiferae (Clusiaceae):

Guttiferae are trees, shrubs or herbs, rarely climbers. Leaves are coriaceous, simple, entire, exstipu­late, opposite or whorled, rarely alternate. Inflorescence cymose or flowers solitary or clustered. Flowers are hermaphrodite or polygamous, or unisexual, actinomorphic, hypo­gynous, with cyclic or Spiro cyclic arrangement of parts; bracts and bracteoles often present; thalamus usually large. Sepals 2-6, free, imbricate.

Petals as many as or double the number of sepals, imbricate. Stamens usually numerous, monadelphous or polyadelphous, in one or more whorls, rarely free; staminodes sometimes present.

Carpels usually 3-5 united to form a superior 3-5 celled ovary, rarely carpels more or fewer; ovules 1-many in each cell on parietal, basal or axile placenta; style very short, with broad stigma depressed above. Fruit capsular or fleshy and indehiscent. Seeds without endosperm and often arillate; embryo straight.

The trees usually have resinous bark. The shrubs of Hypericum are rhizomatous. Clusia is a genus of epiphytic climbers. Leaves of Hypericum are soft and thin; in other genera they are coriaceous and often more or less thick; alternate leaves are found in Caraipa, Kielmeyera, etc. while in other genera they are usually opposite. In many genera bracteoles gradually pass into sepals and in Tovomita sepals and petals cannot be differentiated.

The thalamus is usually broad, convex or concave while in Garcinia it is elongated with the floral parts spirally arranged. Similar spiral arrangement is also found in Clusia criuva Gamb. Galyx is persistent in Mesua. In Hypericum the stamens are many in several fascicles with hypogynous glands in between. The bundles of stamens in Endodesmia are free at base but united to form monadelphous stamens near apex.

Stamens may be free in some Calophyllum or Garcinia species. Ovary one celled in Endodesmia, Ascyrum and Caliophyllum, more in others, some times as many as 15; styles united but distinct in Cratoxylon and Hypericum.

Havetiopsis has the floral parts arranged crosswise with 2 pairs of sepals, 2 pairs of petals and 2 pairs of stamens and 4 carpels in a whorl. Seeds are winged in Cratoxylon, arillate in Garcinia. In some genera the coty­ledons are very small and often obsolete and the radicle is large, e.g. Clusia, Garcinia, Ochrocarpus, etc.

Schizogenous cavities and ducts are found in leaves and stem with resin or oil. The vessels are solitary or in small multiples; perforation plates simple or mixed with scalariform pits. In Clusioideae wood parenchyma is paratracheal, fibres are septate and long, vascicentric tracheids are absent; in Callophylloideae wood parenchyma is apotracheal, fibres are of medium length and vascicentric tracheids are present.

The family comprises 45 genera and about 1000 species. Hypericum the largest genus with over 300 species stretches up to the temperate parts of the world, other genera being restricted to the tropical region.

It is represented in India by several species of Calophyllum, Ochrocarpus longifolius Benth. & Hk.f. Mesua ferrea Linn, (both being called Nag Kesar or Nageswar in Bengali), Garcinia cowa Roxb., G. xanthochymus Hk. f. and several other species of Garcinia. Hypericum is found in the hill, while H. japonicum Thumb, occurs also in the plains.

The family includes several timber trees, e.g. species of Caluphyllum, Mesua, Cratoxylon, Montrouoera, Harungana, Platonia etc. Garcinia mangostana Linn, produces the most delicious fruit mangostene the aril being the edible part.

The drupes of Mammea americana Linn, and Platonia insignis Mart, are also edible. The resinous gum obtained from the bark of Garcinia morella Desr is the gamboge of commerce—an yellow pigment.

A fatty oil is obtained from Pentadesma butyracea Sabine—the W. African tallow tree. Oil is obtained from seeds of Calophyllum and some other genera. Flowers of Ochrocarpus, Mesua and leaves of Harungana madagascariensis have medicinal properties. Calophyllum inophyllum Linn.—the Punnag or Sultan Champa, is planted in parks and gardens and as avenue trees for the beauty of the glossy leaves and flowers.

Guttiferae shows close affinity with Theaceae and Dipterocarpaceae. It resembles Dille­niaceae in floral construction as well as floral anatomy. Engler placed the 3 families in Parietales in the same suborder Theineae while Takhtajan and Cronquist include them in Theales. Hutchinson put them in 3 distinct orders, viz. Theaceae in Thtalei, Chisiaeeae (Guttiferae) in Guttiferales and Dipterocarpaceae in Ochanales.

The family is subdivided into 5 subfamilies by Engler as given below:

I. Kielmeyeroideae:

Flowers usually bisexual; stamens many; ovary 3-5-carpelled, 3-5-celled, style one—Caraipa, Kielmeyera, etc.

II. Hypericoideae:

Flowers bisexual; stamens many, polyadelphous, ovary of 3-5-carpels, 3-5-celled or one-celled, styles free.—Hypericum, Vismia, etc.

III. Endodesmioideae:

Flowers usually bisexual; stamens many, monadelphous above but polyadelphous at base; ovary monocarpellary. —Endodesmia.

IV. Calophylloideae:

Flowers bisexual or unisexual; stamens many free or connate at base; ovary of 1-4 carpels, 1-2-celled, style one.—Mesua, Calophyllum, etc.

V. Clusioideae:

Flowers bisexual or polygamous; stamens many, free or con­nate; carpels and cells of ovary 2 or more, often 12-15, style one very short; cotyledons very small or scaly—Clusia, Garcinia, etc.

In the classification of Bentham and Hooker Hypericineae was a distinct N.O. other than Guttiferae. Engler merged Hypericineae into Guttiferae as one of the subfamilies of the same, e.g. Hypericoideae. Hutchinson and most other workers prefer to treat Hypericaceae as a distinct family the characters of which are given below:

Trees, shrubs or herbs, rarely lianes with resinous sap. Leaves simple opposite or whorled, exstipulate, often pellucid-punctate. Inflorescence a terminal, rarely axi­llary cyme, or flowers solitary. Flowers regular, hermaphrodite. Sepals 4-5, imbricate, often connate at base, unequal.

Petals as many as sepals sometimes clawed, claw with nectar-pit or groove, free, imbricate or contorted. Stamens many, hypogynous, usually polyadelphous; filaments in each bundle connate, rarely monadelphous; anthers 2- celled.

Ovary superior, 3-5-carpelled, syncarpous, 3-5-celled or only 1-celled, ovules many in each cell, anatropous, on axile, rarely parietal placentation, styles free or basally connate. Fruit a capsule or berry. Seed without endosperm and with straight or curved embryo.

Family # 5. Dipterocarpaceae:

Dipterocarpaceae are trees, usually very tall, rarely shrubs; branching at first monopodial, later sympodial; younger parts hairy. Leaves are simple, coriaceous, alternate, stipulate, usually pro­minently penninerved, frequently with domatia in axils of nerves. Inflorescence is a racemose panicle, rarely cymose, terminal or axillary, with caducous bracts.

Flowers are hermaphrodite, regular, with a broad receptacle, 5-merous. Sepals 5, unequal, imbri­cate or valvate, slightly connate at base and adnate to the ovary, persistent and more or less enlarging in fruit in the forms of wings. Petals 5, imbricate or contorted, free or connate at base.

Stamens 5, 10, or 15, sometimes more, in one or more whorls, development centrifugal, usually connate at base, frequently adnate to the base of petals; androgynophore often present; anther lobes unequal, connective usually produced at the apex.

Carpels 3, forming a syncarpous 3-celled ovary, rarely 1-celled; ovary superior rarely semi-inferior; ovules 2 or more in each cell on axile placentation; style often trifid at apex, sometimes on a stylopodium; stigma usually obscure, 3 or 6-lobed.

Fruit nut-like, with all or some of the persistent sepals enlarged to form wings. Seeds without endosperm; embryo fills the seed, cotyledons often twisted, lobed or laciniate, unequal, enclosing the radicle.

The trees are usually evergreen but Shorea is deciduous. Stipules usually caducous but in some species of Shorea they are persistent; in Dipterocarpus the stipules are large and enclose the young bud.

Five stamens are met with only in Monoporandra; in most genera there are 15 stamens in 3 whorls, often stamens are 20 in 4 whorls, rarely more stamens are found. Hopea recopei Roxb. has monadelphous stamens. In Marquesia ovary ii one-celled and the placentation is parietal. In Vatica ovary is sunk in the receptacle.

Floral formula:

The resin ducts are lined with epithelium layer. The vessels are mostly solitary, sometimes in small-groups and rarely in radial rows; these have simple perforations and alternate intervascular pitting. Vascicentric tracheids are often present. Some­times vascular bundles are present in cortex.

The family consists of 16 genera and over 500 species found in Tropical Africa and S. E. Asia. Over 50 species occur in eastern and southern parts of India the most important being Shorea robusta Gaertn. f.—the Sal tree which grows wild and is culti­vated for the valuable timber.

Dipterocarpus is Indo-Malayan, the species of which are very tall branching only near the top. About 10 species occur in eastern parts of India and are locally called Garjan tree. Hopea, Vatica, Vateria, etc. are other genera having Indian species.

Most species yield hard and durable timber, Skorea robusta being most important. Turpentine and dumar resin are obtained from Shorea robusta and S. koordarsii. Gum- resin obtained from Vateria indica Linn, is used to make copal varnish. Fatty oil is obtained from the seeds of Shorea aptera and Vateria indica Linn.

Starchy seeds of Vateria, Vatica and Doona are edible. A strong smelling dense balsam known as “Chooa” is obtained from Isauxis lancaefolia King. “Borneo camphor” or “Sumatra camphor”— the yellow camphor is the product of crystals deposited in the wood of Dryobalonops aromatica Gaertn.

Dipterocarpaceae is closely related to Guttiferae and Theaceae. From the former it differs in alternate leaves and presence of stipules. From Theaceae it differs in having resin ducts in the wood and pith, and fruit usually winged. The prominent nerves of the leaves resemble those of Dilleniaceae to some extent.

It is also close to Ochnaceae having somewhat similar arrangement of floral parts. It has some affinity with Ancistrocladaceae also, which family was included under Dipterocarpaceae in the old classification of Ben­tham and Hooker.

According to Hutchinson Dipterocarpaceae is much closer to Ochnaceae and Ancistrocladaceae which 3 are put by him in Ochnales, than to Theaceae and Clusiaceae (Guttiferae) which are placed by him in Theales and Guttiferales respec­tively. Further he places Theales and Ochnales side by side while Guttiferales is placed in another group.

Engler divided Dipterocarpaceae into 2 tribes as noted below:

I. Monotoideae:

Anthers dorsifixed; gynophore present; wood without resin ducts; rays uniseriate.—Monotes, Marquesia. (Tropical Africa).

II. Dipterocarpoideae:

Anthers basifixed; gynophore absent; wood with inter­cellular resin ducts; rays multiseriate.—Shorea, Hopea, Dipeterocarpus, etc. (S. E. Asia).

Family # 6. Tamaricaceae:

Tamaricaceae are shrubs or perennial herbs, rarely short trees: Leaves alternate, exstipulate, very small and scale-like or linear, sessile, entire, addressed and usually glaucous. Inflore­scence spikate or racemose, terminal or axillary near the apex of branches, ebracteate. Flowers are small and inconspicuous, regular, bisexual, rarely unisexual, hypogynous, pentamerous or tetramerous.

Sepals 4-5 free, imbricate; petals as many as sepals, free, imbricate. Stamens 4 or 5, or double this number, or numerous, inserted on a disc, free or connate, anther bilocular, dehiscing longitudinally and laterally.

Carpels 4-5 or only 2, united to form a superior unilocular ovary; ovules few or many, anatropous, ascending on basal or parietal placentas; raphe ventral; styles free or united below and branched above. Fruit a capsule dehiscing along the dorsal surface. Seeds hairy with a straight embryo and with or without endosperm, rarely winged.

This is a small family of about J 20 species under 4 genera, halophytic or xerophytic, inhabiting the steppes of C. Asia, and on sandy soils on sea-shores on Med. region and banks of large rivers in Asia. In India it is represented by Tamarix Troupii Hole, T. articulata Vahl., Myricaria germanica Linn. etc.

Economically the family is not very important. Those attaining tree-size yield Valuable timber, e.g. Tamarix articulata. The bark and galls of this tree as well as of T. gallica Linn, are much used for tanning and dyeing. T. gallica var. mannifera Ehren of W. Asiatic countries produce a manna much eaten by the local people and has medicinal properties. The plants being fast growing are a source of fuel and serve, as sand-binders.

The affinity of the family with Frankeniaceae has been recognised by almost all workers. Hutchinson and Takhtajan place these 2 families along with Fouquieriaceae in a distinct order Tamaricales which is considered to have been derived from Bixaceae and allied families.

Family # 7. Bixaceae:

Bixaceae is a small family of trees and shrubs with reddish sap. Leaves are simple, alternate, stipulate, palmately nerved; petioles usually long and covered with tufted hairs. In­florescence is a terminal panicle. Flowers are large and showy, actinomorphic, bisexual and hypogynous. Sepals 5, free imbricate, deciduous, bi-glandular at base.

Petals 5, free, imbricate or twisted. Stamens many, free; anthers bi-locular, theca narrowly horse-shoe shaped, opening by short slits at the apical bend. Carpels 2-4, united to form a superior unilocular ovary; ovules many anatropous, on parietal placentas; style slender and curved, stigma thick, bilobed.

Fruit a loculicidal capsule, setose. Seeds with a fleshy red testa; funicle thick; endosperm scanty, starchy; cotyledons large, curved at apex.

This is a unigeneric family with only 4 species indigenous to tropical America. Bixa orellana Linn. The Annatto (Beng. Latkan) is cultivated in almost all tropical countries as an ornamental plant and for the dye? obtained from the seed-coat. The dye is used in colouring clothes, cheese, butter and sweet meats.

The family is allied to Cochlospermaceae, Cistaceae, Flacourtiaceae and also to Violaceae to some extent. Both Takhtajan and Cronquist include the family in Violales while Hutchinson placed it – Bixaies stating that this order originated directly from Dilleniales.

Family # 8. Violaceae:

Violaceae are annual or perennial herbs, rarely erect shrubs or climbers, very rarely trees. Leaves are simple alternate or opposite, stipulate, often basal and variously lobed and laciniate; stipules often large and foliaceous. Inflorescence an axillary spike or raceme or panicle, or flowers solitary; bracts and bracteoles present.

Flowers are pentamerous, actinomorphic or zygomorphic. Sepals 5, free of slightly connate, imbricate, persistent; the posterior often caducous. Petals 5, free or slightly connate below, equal or unequal, in the latter case the anterior petal is much larger and spurred or gibbous.

Stamens 5, connivent in a ring round the ovary; filaments often broad and thin, sometimes connate in a tube, very rarely diadelphous; the connectives of the outer pair of stamens often spurred or appendaged.

Ovary superior, of 2-5, usually 3 carpels, syncarpous, unilocular; ovules 3-oc on parietal placentas, anatropous with 2 integuments and ventral raphe; style terminal , simple or in zygomorphic flowers sygmoid or thickened upwards; stigma variable.

Fruit a capsule splitting into 3 boat-shaped valves, rarely berry. Seeds with hard and shining testa, often with an elaiosome in the form of an appendage of the raphe; endosperm copious, fleshy; embryo straight.

Anchietia and Agatea are climbers, Rinorea and Paypayrola are trees and Hymenanthera are erect shrubs. Some species of Viola are rhizomatus and a few are stoloniferous. Alsodeia, Rinorea, etc. have actinomorphic flowers. In Paypayrola corolla is gamopetalous. Androecium in Agatea and Leonid is monadelphous and in Anchietia it is diadelphous. Fruit is a berry in Hymenanthera, Leonia, etc.

In the case of irregular flower nectar is stored in the hollow spur of anterior petal and this is secreted by the spurs of the anterior anthers. The showy flowers and the nectar attract the insects which pollinate the flowers.

In some species self-pollination is effected by means of cleistogamous flowers which appear later in the season after the normal flowering is over. These are small and aperalous with 2 perfect stamens and 3 staminodes.

Floral formula:

Calcium oxalate crystals are often present in leaf-mesophyll. Stone cells are present in the mechanical tissue in most genera and groups of schlerenchyma fibres form a closed pericyclic nag together with stone cells. The vessels are irregularly distributed.

Those in the triba Violeae have simple and repand scalariforrn perforations on transverse walls while in the triba Rinoreae there are many scalariforrn perforations. The fibres are septate with simple and bordered pits.

The family consists of about 1000 species under 18 genera distributed in the tropical’ and temperate parts of the world, a few occurring in the arctic region. The largest genus Viola with 500 species is widely distributed, only 15 of which occur in India in the hills. Hybanthus enneaspermus Fragm. a small perennial herb is common in the plains.

Many species of Viola are cultivated for the showy flowers. V. tricolor Linn, is the Pansy, many hybrids of the same are met with. V. odorata Linn, is sweet scented and yields an essential oil. A few species of S. American Hybanthus are good_tsubstitutes of Ipecacuan­ha plant. Roots of Anchietia salutaris are emetic and are used to treat sore throat and lymphatic tuberculosis.

The family appears to be closely related to Flacourtiaceae. Hutchinson places the family in an order of its own, viz., Violates which is next to his Tamaricales. The Violates of Takhtajan includes Flacourtiaceae and Bixaceae as well as Stachyuraceae, Cochlospermaceae and Cistaceae tracing their affinity with Violaceae.

Affinity of Violaceae with Flacourtiaceae is also recognised by Cronquist who includes so many other families in his Violates besides Violaceae and Flacourtiaceae- Violaceae appears to be related also to Resedaceae.

The family is divided into 2 subfamilies as given below:

Subf. I Violoideae: Stamens free or slightly united, anthers introrse.

Tribe 1. Rinoreae Flowers regular, sepals free, fruit usually a capsule—Rinorea, Gloeospermutns, etc.

Tribe 2. Hymenantheriae: Sepals united at base, fruit a berry—Hymenanthera, etc.

Tribe 3. Violeae: Flowers zygomorphic, posterior petal largest and spurred, posterior pair of stamens larger and appendaged— Viola, Hybanthus, etc.

Subf. II Leonioideaet Stamens monadelphous, anthers sunk in the staminal tube—Leonia.

Family # 9. Flacourtiaceae:

Flacourtiaceae are trees and shrubs often with spiny branches; rarely climbing. Leaves are simple, leathery, alternate, usually distichous, rarely opposite or whorled, stipulate or not. Inflorescence axillary or terminal, racemose or cymose, or of a mixed type, rarely corymbose; rarely flowers solitary.

Flowers are bisexual, sometimes polygamous or unisexual and monoecious or dioecious, regular, 4-5-merous or with several members in each whorl, cyclic or sometimes partly spiral; peduncle often jointed near base; axis convex with a disc or a ring of glands or scales between corolla and androecium.

Sepals 4-15, persistent, free or united, imbricate or valvate. Petals as many as or twice as many as sepals or more, free, imbricate, 01 petals absent. Stamens many, in one or more whorls, free or polyadelphous, the bundles being antipetalous; filaments long, very rarely petaloid; connective of anthers sometimes appendaged, usually opening by lateral slits; very rarely stamens as many as an alternate to sepals.

Ovary of 2-10 carpels, unilocular or rarely multilocular, superior or scrpiinferior or rarely inferior; ovules anatropous, many or few on parietal placentas which often project inside and sometimes meeting in centre to form multilocular ovary; styles as many as carpels, free or united, or stigma-sessile. Fruit a berry or capsule. Seeds often arillate, with copious endosperm and straight embryo.

The 2 genera Streptothamnus and Dioncophyllum are climbers while all others are shrubs or trees. The stipules when present are caducous except in Phyllobotrium where they are large and persistent. Bembicia has a dense corymbose inflorescence with an involucre of scaly bracts.

The inflorescence is epiphyllous in Phyllobotrium. Monoecious and dioecious plants occur in many genera, e.g., Flacourtia, Xylosma, Trichostephanus, Pangium, Hydnocarpus, etc., while many genera have hermaphrodite flowers. In Abatia, Flacourtia, Trichostephanus, Casearia, Samyda, etc., the flowers are apetalous and in the last genus the sepals are petaloid.

In Paropsia the disc is more or less tubular and like a gynophore, and often a corona is present. In Paropsiopsis and Soyauxia androphore is also present. Bembicia has true epigynous flowers and calyx tubular with stamens on the mouth of calyx-tube.

Calcium oxalate crystals are found in the epidermal cells of many genera. Resin containing cells are found only in Casearia resinifera. The pericycle is usually composed of strands of fibres while isolated fibres are present in many genera. Fibres are septate with simple pits. The vessels are solitary or in rows of 2-3 cells radially arranged; perforations simple, rarely scalariform; intervascular pitting also scalariform.

Floral formula for a typical bisexual flower:

Flacourtiaceae contains over 1200 species under 95 genera, distributed in the tropical and subtropical parts of the globe. In India it is represented by several species in the plains, e.g., Gynocardia odorata R.Br., Xylosma longifolium Clos., Casearia tomentosa Roxb., several species of Flacourtia and several species of Hydnocarpus.

The family is important economically for a few useful plants. Oil obtained from the seeds of different species of Hydnocarpus and Gynocardia are efficacious in treating skin diseases. The chalmoogra oil obtained from Gynocordia is useful in leprosy. Dovya- lis cajfra Warb. produces edible fruits called Key-apples.

Berries of different species of Flacourtia are also edible. Species of Pangium which have fragrant flowers are poisonous. Fruits of Casearia tomentosa Roxb. are also poisonous and are used to stupefy fish before catching. C. praecox Griseb is the Box-wood that yields valuable timber. The juice of the fruit of Hydnocarpus venenatus is strongly intoxicating. Oncoba has large flowers and edible berries.

Flacourtiacea is closely related to Bixaceae. Many genera of Flacourtiacea were formerly iucluded in Bixaceae. These genera together with those under Samydaceae were brought under a new family Flacourtiaceae established by Gilg who placed it among other families of Parietales.

Hutchinson and Takhtajan place Flacourtiaceae in Bixales while Cronquist included it in his Violates where he puts Bixaceae also and many other families. Flacourtiaceae appears to be close also to Tiliaceae and Elaeocarpaceae and to Euphorbiaceae to some extent.

Gilg classified the family Flacourtiaceae into 12 tribes as noted below:

Family # 10. Passifloraceae:

Passifloraceae are climbing plants, herbaceous or shrubby, often lianous, climbing by axillary tendrils. Leaves are alternate, simple or compound, palminerved or pinninerved, palmilobed or entire, stipulate; petiole often glandular. Flowers are axillary, solitary or in pairs, with persistent bracts, regular and bisexual or rarely unisexual; receptacle very prominent cupular or tubular or saucer-shaped.

Sepals usually 5, free or connate at base, often petaloid or fleshy, imbricate, membranous at the margin. Petals as many as sepals, free or slightly connate at base, imbricate, often smaller than sepals, rarely absent. A fleshy concave or cup-shaped corona is usually present between the perianth and androecium.

Stamens as many as petals and opposite to them, or more, arising from the base of the corona or rim of the receptacle or from the apex of the gynophore (thus forming an androgynophore), free or basally connate; anthers 2-celled dehiscing longitudinally; staminodes rarely present.

Carpels 3-5, syncarpous; ovary superior, raised on a gynophore of and rogynophore, unilocular; ovules anatropous, numerous on parietal placentas which are usually intruding; styles as many as carpels with capitate or discoid stigmas, or styles united or rarely absent. Fruit a berry or loculicidal capsule. Seeds with fleshy endosperm and straight embryo, rarely with mucilaginous and pulpy aril.

The tendril is a metamorphosed branch or it is part of the axis of inflorescence; it corresponds to the terminal flower of a dichasium or the first flower of a monochasium.

Tendrils are absent in few genera, e.g. Tryphostemma, Machadoa, Adenia, etc. Adenia kernmanthus is erect while in a few other species of the same genus tendrils are replaced by thorns. Adenia globosa is another tendril-less species which is xerophitic and has a globular erect fleshy stem and small leaves.

The corona is interpreted to comprise the hypanthium and all accessory structures situated between the perianth and stamens. The hypanthium is of appendicular origin and not expansion or concavity of the receptacleor torus. The whorls of sterile structures within the, petals are called the radii, the shorter whorls within the radii are the pali, inside the pali there is usually a delicate membrane which is the operculum.

The oper­culum usually closes the nectary-chamber from outside. The 3 parts of the corona, radii, pali and operculum represent extra developments of the perianth parts and no part of the androecium.

The annulus within the operculum is the nectariferous region. At the base of the androgynophore or inside the hypanthium there is a narrow rim or cup which is often lobed. This is called limen and is probably staminodial in nature.

In some genera there is a prominent swelling of the node above the limen. This is called trochlea. The family consists of about 600 species under 11 genera mostly continued to tropical America while a few are found in Africa, Asia and New Zealand.

In India several species of Pass flora originally of Tropical America have established themselves and are growing wild, e.g. P. suberosa Linn., P.foetida Linn. etc. Modeca triloba Roxb. is indigenous to eastern India. Passiflora caerulea Linn, is cultivated in the gardens for the beautiful flowers while P. edulis Sims, is cultivated in the hills at lower elevations for the edible fruits.

P. ligularis is another species of which the fruits are edible. A few have showy flowers, viz. P. racemasa Brot., P. incamata Linn., P. holosericea Linn., P. caerulea Linn., etc. and are cultivated in the gardens. Otherwise the family is not of much economic importance.

Passifloraceae is closely related to Caricaceae and Turneraceae. According to Hutchin­son the family Passifloraceae is closer to Malesherbiaceae and Achariaceae than to any other families of Parietales of Engler and he places these 3 families in a distinct order Passiflorales.

Takhtajan also recognises the close relationship of Malesherbiaceae and Achariaceae with Passifloraceae as also of Caricaceae and Turneraceae and includes these five families in his Passiflorales. Cronquist places Passifloraceae in Violales where several other families, Caricaceae. Turneraceae, Malesherbiaceae and Achariaceae are also included.

Caricaceae:

Soft wooded trees with milky sap; trunk rarely branched with foliage in a terminal crown, having the appearance of a palm tree. Leaves large, alternate and crowded near the apex of the stem, long petioled and palmately lobed, exstipulate; petiole usually fistular. Panicles or corymbs axillary, or flowers clustered. Flowers hermaphrodite or unisexual, polymorphous. Calyx gamosepalous, very small, 5-lobed.

Corolla gamopetalous and tubular in the male flowers and free or connate near base in female flowers, segments or lobes 5, twisted or valvate. Stamens usually 10 in 2 whorls, the inner often absent; the anthers usually sessile, 2-celled, dehiscing longitudinally, inserted on the throat of the corolla tube or the filaments attached near the base of the ovary; con­nectives often produced upwards.

Carpels 5, syncarpous in a superior unilocular ovary; ovules ∞, anatropous, on parietal placentas which sometimes intrude inside; styles 5, short, with broadly cuneate or fan-shaped simple or five-partite or fimbriate stigmas.

Fruit a large globose or pyrifoim or cylindric berry with a large cavity inside and many small seeds. The seed has 2 coats, an outer fleshy one known as sarcotesta or false aril and the inner hard one the sclerotesta which is tubercled or echinate with straight or hooked spines; embryo straight and endosperm fleshy.

The trees are short, rarely reaching a height of 10 mtr; the trunk is rough with leaf scars. Mocinna helerophylla Cervo is a climbing shrub. Carica lanceolata Hiern. has simple entire leaf. In Cylicomorpha and Jacaratia the stem is spiny.

The flowers are poly­morphous and 4 different types of flowers are found:

(1) Male plants having only staminate flowers in clusters on pendant racemes, stamens 10 in 2 series with sessile anthers, rudimentary ovary usually present;

(2) Female plants with sub-sessile pistillate flowers which are solitary or in few-flowered corymbs in axils of leaves, ovary large, globose with 5 sessile fimbriate stigmas, fruits globose or pyriform or ovoid;

(3) Simi­lar to (2) but with a long many flowered panicle with several 5-6-flowered corymbs, 17 [College Botany III] flowers usually bisexual, stamens 10 with sessile anthers, situated at base of petals, fruit long, cylindrical;

(4) Flowers are polygamous, some male flowers have 10 stamens with sessile anthers at the throat of an elongated corolla tube, others with only 5 long filament stamens attached near the base of the ovary.

Such flowers with variable morphology are met with in same species, e.g. Carica papaya Linn. In Carica quercifolia Solms. the ovary is 5-celled. The female flower of C. pentagyna Heilb. has a much longer corolla-tube than the male.

Branched and articulated latex tubes occur in the tissues in most part of the plant. The cortex is composed of collenchymatous cells with isolated strands of fibres. Xylem vessels are large and have simple perforations.

Pith rays are parenchymatous and separate the vascular bundles. Caricaceae is a small family of 4 genera and 55 species occurring in tropical America and Africa. It is represented in India only by the cultivated species Carica papaya Linn.

The family was formerly included in Passifloraceae but later treated as a distinct family allied to Passifloraceae. Hutchinson places Caricaceae in Cucurbitales which order however is close to Passiflorales according to him. Cronquist includes it in his Violales where in with several other families Passifloraceae and Cucurbitaceae are also included.

The well-known fruit tree Carica papaya Linn, belongs to this family. It is much cultivated in India and other tropical countries for the delicious fruit as well as for the alkaloid papain obtained from the latex. C. cundinamarensis Hook. f. is another species producing edible fruits. No other species is of any economic importance.

Family # 11. Begoniaceae:

Begoniaceae are succulent herbs or low shrubs, erect or creeping, sometimes accaulescent and often rhizomatous or tuberous; stem more or less jointed. Leaves are alternate, usually 2-ranked, simple, palminerved and often palmilobed, stipulate, asymmetrical, petiolate; stipules caducous or early deciduous. Cymes axillaty, dichotomous. Flowers are uni­sexual, zygomorphic or actinomorphic, epigynous.

Male flower with 2 petaloid valvate sepals and 2 valvate petals smaller than sepals, rarely sepals and petals more than 2, usually free or rarely connate; stamens ∞, in more than one whorl, free or the fila­ments connate at base; anthers bilocular, variously shaped, basifixed, dehiscing longitudinally or by pores, connective often produced.

Female flower with 2-8 perianth segments in one series, all petaloid, imbricate or rarely valvate, free; ovary inferior, of 3-5-carpels, syn­carpous, 3-locular, with 3 wings, ovules ∞, on simple or lobed usually axillary placentas, anatropous; styles distinct or basically connate, the stigmas strongly papillose and often twisted. Fruit a loculicidal winged capsule, rarely a berry. Seeds with straight oily embryo and without endosperm.

Calcium oxalate and calcium carbonate crystals are common in the tissues of the leaves.-Begonia socotrana Hook, has orbicular peltate leaves. Sepals and petals are united in Begoniella and also in the female flower of Symbegonia. The female flowers of Begonia have bracts and bracteoles. In Hillebrandia sepals and petals are 5 each, the ovary perigynous and unilocular with 5 parietal placentas.

Extra cauline vascular bundles occur outside the normal ring of bundles. These unite with the vascular ring at the nodes. Vessels are of medium sized and perfora­tions are simple or scalariform at the end walls.

The family consists of 5 genera and 920 species about 900 of which belong to the genus Begonia which is distributed in the temperate and tropical regions of the world. Hillebrandia is a monotypic genus of Hawaii while Symbegonia is another monotypic genus occurring in New Guinea. In India the family is represented by over 50 species of Begonia. The plants of this family prefer a damp warm situation.

The family is not economically important except that a few species of Begonia are cultivated in the gardens for the beautiful flowers, e.g. B. rex Putz., B. tuberhybrida Voss, B. semperflorens Link & Otto, etc. They are of further horticultural interest for the fact that new plants can be raised easily by leaf cuttings.

The family is allied to Datiscaceae. It is also related to Cucurbitaceae according to Rendle, Hutchinson, Cronquist and others although according to Engler Cucurbitaceae is far removed from the families included in his Parietales.