List of Gymnosperms

Here is list of sixteen gymnospems:- 1. Cycas 2. Ginkgo 3. Pinus 4. Cupressus 5. Thuja 6. Juniperus 7. Cryptomeria 8. Podocarpus 9. Taxus 10. Cephalotaxus 11. Picea 12. Araucaria 13. Cedrus 14. Abies 15. Ephedra 16. Gnetum.

1. Cycas:

Vegetative Structure:

The plant is arboreal, un-branched palm tree like. The stem is columnar and also covered by an armour of persistent leaf bases and bearing a crown of large leaves above. The leaves are simple pinnate type and spirally arranged. Leaflets are tough, leathery and with midrib but no lateral veins.

Leaves are alternate with scale leaves (dimorphic). Young leaves show circinate ptyxis (vernation). Both normal lap roots and coralloid roots are present.

Stem Anatomy:

In T.S. through young stem, there are persistent leave bases, a large cortex, large pith and scanty rings of wood in between, cortex and pith are parenchymatous and show numerous mucilage canals. The vascular bundles are conjoint, collateral and open type.

Coralloid Root Anatomy:

T.S. through coralloid root of Cycas shows the following layers – epidermis, massive parenchymatous cortex which surrounds a protostele at the centre. There is a conspicuous algal zone in the cortical region.

Leaf Anatomy:

In T.S. through the leaf of Cycas, the following layers are noted: Two layers of cuticularised epidermis, of which the lower epidermis has sunken stomata; both pallisade and spongy mesophyll cells; transfusion tissue and conjoint, collateral, closed vascular bundle surrounded by bundle sheath. (Fig 7.1).

Reproductive Structure:

The plant is dioecious, i.e., male and female strobili are formed on separate plants.

Male Sirobilus:

It is compact cone like. Each cone is quite large and up to 50 cm in length. It is developed at the apex of the stem. Each strobilus possesses a central axis on which spirally arranged megasporophylls are compactly set. A microsporophyll is about 5 cm long and 25 mm wide.

On the under-surface of each microsporophyll, there are numerous microsporangia which are borne in groups (sori) of 3 or 4 each. Microsporosagia are unilocular and contain many microspores or pollen grains.

Female Strobilus:

It is lax, not compact cone like. The megasporophyll is a leaf like flattened structure (15 – 30 cm long) and it bears megaspores (1 to 5 pairs) laterally. Both sporophylls and ovules are covered by yellowish hairs. The megasporophylls arise at the tip of the plant acropetally forming a loose crown.

Ovule:

It is orthotropous, about 6 cm long and 4 cm in diameter. It possesses an integument which is united with nucellus except at the top. The integument is 3 layered – outer soft coloured, middle stony, and inner soft layer. There are three vascular strands at the base of the ovule. There is a conspicuous pollen chamber at the micropylar end (Fig 7.2).

Identification:

Plants with stout trunks, Cortex massive, wood less developed, leaves megaphyllous, micro-sporophylls form compact cone-like strobilus.

CLASS: CYCADOPSIDA

Stout stem trunk bears persistent leaf bases and a crown of leaves at the top.

ORDER: CYCADALES

Palm-like plant habit with fern-like foliage.

FAMILY: CYCADACEAE

Leaves pinnately compound, leaflets with single median veins, and no lateral veins, megasporophylls not forming any compact cone, ovules on megasporophyll margin.

GENUS: CYCAS

2. Ginkgo:

Vegetative Structure:

Plants are deciduous trees, somewhat conical and sparely branched. Branches are irregularly whorled or produced at indefinite intervals some erect and developing duplicate leader. Branchlets are horizontal or drooping. Leaves are fan-shaped, resembling a much enlarged pinnule of a maiden-hair fern, petiolate, and usually 5 – 7.5 cm long.

The margin of the leaf is divided into 2 large lobes, usually undulated or irregularly notched, with no midrib, but with numerous branching parallel veins. Some scale leaves are present. Shoot dimorphism is prominent – long leafless shoot and short or dwarf leafy shoot. Long shoot may terminate in short shoots and short shoot may develop into long ones.

Stem Anatomy:

Internally, the structure of long-shoot and short or spur shoot varies greatly. In T.S. through long shoot, there is a relatively small pith and cortex. Its wood is harder and there are only few mucilage cavities. The vascular cylinder is an endarch siphonostele and tracheids have one or two rows of bordered pits.

There is conspicuous wood and periderm formation. In dwarf shoot, however, there is little secondary growth but cortex and pith zones are quite prominent.

Leaf Anatomy:

T.S. through leaf blade shows two epidermal layers, lower epidermis with stomata, conspicuous mucilage tissue, pallisade mesophyll cells, transfusion tissue and exarch, collateral vascular bundles covered by sheath (Fig 7.3).

Reproductive Structure:

The plant is dioecious. Strobili are borne in the axils of the scale leaves in the crown of the dwarf shoots forming clusters there.

Male Strobilus:

It consists of an axis bearing numerous spirally arranged elaborate micro-sporophylls. Each microsporophyll is slender, and bears two pendent microsporatigia. Pollen grains are wingless.

Female Strobilus:

It is pedunculated and bears the ovules in pairs in young stage, but only one matures. Ovule is covered by bud scale. Each Ovule is surrounded by a collar-like growth. Seeds are with unequal cotyledons.

Ovule:

Mature Ovule has the following structures – prominent nucellus, a large pollen chamber surrounded by a beak, single integument which is free from the nucellus at top. Integument is three layered – outer green fleshy layer, a thin hard middle layer, and a thin fleshy inner layer. There are two vascular strands supplying the base of the integument. (Fig 7.4).

Identification:

Plants branched, tree like, leaves simple and microphyllous, wood development prominently.

CLASS: CONIFEROPSIDA

Leaves deciduous, broad and fan shaped, (presence of motile sperm cells), male and female strobili not compact cone like.

ORDER: GINKGOALES

Leaves with parallel veins, tracheids with pittings, ovules with collar.

FAMILY: GINKGOACEAE

Seeds with unequal cotyledons, pollen grains wingless, leaves bilobed.

GENUS: GINKGO

3. Pinus:

Vegetative Structure:

The Pinus tree shows a single stout, cylindrical stem covered by a scaly bark and regular lateral branches of unlimited growth termed as “long shoots”. From the long shoot young branches of limited growth develop. These are termed as “dwarf shoots”. Long shoots show leaf scars and scale leaves while dwarf shoots have scale leaves and long needle shaped leaves in fascicles (two to five) (Fig 7.5.).

Stem Anatomy:

Transverse section through the young stem shows almost identical tissue arrangement as in typical dicotyledonous stems. It has a number of tissue zones – epidermis, cortex with resin ducts, ectophloic siphonostelic endarch bundles arranged in a ring, conjoint collateral open, vascular bundles, and a distinct parenchymatous pith.

However, T.S. through mature stem shows massive secondary growth like that of dicotyledonous plant stems. There is a distinct extrastelar bark formation and also a thick zone of secondary wood with resin ducts. The secondary wood is devoid of vessel elements. In L.S. through wood, there are distinct bordered pit thickenings on tracheid’s called “Bars of Sanio”. There is predominance of secondary medullary ray cells in wood.

Leaf Anatomy:

Leaves are xerophytic, centric and needle shaped. They are more or less triangular in transverse section. The T.S. through leaf shows the following tissue zones – cuticularised epidermis with deeply sunken haplocheilic stomata, hypodermis, mesophyll cell zones with thin walled crenately lobed chlorophyllose cells and resin canals, endodermal layer with casperian strip, 1 – 2 collateral closed vascular bundles surrounded by pericycle and transfusion tissue. (Fig 7.6).

Reproductive Structure:

The plant is monoecious.

Male Strobilus:

They are yellow or reddish in colour, cylindrical in shape and produced in clusters around the base of young shoots. A median longitudinal section reveals that a male strobilus or cone consists of a slender axis which bears numerous spirally arranged microsporophyll’s. Each microsporophyll has two microsporangia on its abaxial surface and subsequently within each microsporangium microspores or pollens (with a pair of inflated wings) are developed.

Female Strobilus:

It is conspicuously larger than male cone and usually terminal or sub-terminal in position on the stem. A median longitudinal section through female strobilus or cone shows a central axis on which a number of spirally arranged tough megasporophylls (Ovuliferous scales) are arranged. Each ovuliferous scale bears two ovules with wings on its upper surface. The mature ovuliferous scale is woody. The lower smaller bract scale disappears before the cone ripens.

Ovule or Mega-sporangia:

A median longitudinal section through mature ovule shows that each ovule has a mass of nucellus covered by an integument growing from its base. The integument is open at the top forming a micropyle and is free from the nucellus in the upper part of the ovule.

The integument shows three layers – an outer fleshy, a middle stony and an inner fleshy. The female gametophyte shows a pair of archegonia towards the micropylar end. There is only one vascular trace for the female gametophyte, nucellus and integument layers (Fig 7.7).

Identification:

Plants branched, tree like, leaves simple microphyllous and wood well developed.

CLASS: CONIFEROPSIDA

Evergreen plants with spreading branches; stem with massive secondary wood and characteristic resin canals, male and female strobili compact and cone like.

ORDER: CONIFERALES

Leaves needle like, arranged in tufts of 2 – 5 on young branches; monoecious, cones mostly woody; ovuliferous scale free from bract scale; pollen remains mostly winged.

FAMILY: PINACEAE

Leaves evergreen, acicular, in bundles (2-5), pollen grains winged, female cone pendulous, woody and persistent.

GENUS: PINUS

4. Cupressus:

Vegetative Structure:

Cupressus is an evergreen tree species with finely divided branchlet systems arising at various angles. The leaves are persistent, small, scale-like, adpressed; mostly in opposite pairs. Anatomically stem is identical with Pinus sp., wood is light yellow to brownish, there are conspicu­ous medullary rays, and resin canals in the wood.

Reproductive Structure:

The cones are globose or sub-globose composed of several scales, male and female strobili appear on the same tree.

Male Strobilus:

They are small, cylindrical and situated terminally on branchlets, micro-sporophylls are spirally arranged on the axis. Each microsporophyll bears 2 to 6 microsporangia and they are somewhat peltate in shape. Pollen grains are not winged.

Female Strobilus:

Female cones are on short branches bearing a few peltate scales with ovules in several rows at the base. Cones dry, globose or ellipsoid, formed of 6 – 12 woody, shield like ovuliferous scales fitting closely together by their margins while growing, but separating when mature, each consists of a central boss or triangular process on the outer surface, each scale with numerous winged seeds. The cones are retained on the branches for an indefinite period after maturing, which takes place during the second year (Fig 7.8).

Identification:

Plants branched trees, leaves simple microphyllous, wood well developed.

CLASS: CONIFEROPSIDA

Plants evergreen, stems with massive secondary wood and characteristic resin canals, male and female strobili compact and cone like.

ORDER: CONIFERALES

Leaves persistent, small, scale like, opposite or in whorls, bract scale intimately fused to the ovuliferous scale, pollen grains not winged.

FAMILY: CUPRESSACEAE

Female cones dry, globose to subglobose, ovuliferous scale woody; peltate and with many winged seeds.

GENUS: CUPRESSUS

5. Thuja:

Vegetative Structure:

The plants are mostly evergreen, branched trees. Branchlets are slender, tough, divided near the apex into fine spray, smaller branchlets deciduous with the leaves after several seasons.

Leaves are small, scale-like, overlapping in 4 rows of 2 opposite sets, the upper and lower ranks flattened or grooved, the side ranks rounded or keeled. The foliage is usually glandular and aromatic. Thin bark is present, fissured only on old trees, outer bark normally shows scaling in patches of irregular shape but inner bark is fibrous.

Reproductive Structure:

Strobili or cones are globose or subglobose. They are formed on different branchlets of the same tree.

Male Strobilus:

It is somewhat reddish, cylindrical or globose. It is normally situated on branchlets near the base of the shoot and composed of 3 – 6 pairs of microsporangia, pollen grains are not winged.

Female Strobilus:

It arises from short terminal branchlets. It is small, green to purplish, composed of a few opposite pairs of leaf-like scales. Mature cones are solitary and made up of 3 – 10 pairs of ovuliferous scales. Bract scales are fused with the ovuliferous scales. Cones are dry and ovoid to oblong. Seeds are small, thin and winged or wingless, but attached to the edge of the ovuliferous scale. Cone scales possess thickened or ridged apex and a very fine spine (Fig 7.9).

Identification:

Plants branched trees, leaves simple microphyllous, wood well developed.

CLASS: CONIFEROPSIDA

Plants evergreen, stem with secondary wood and resin canals, male and female strobili compact and cone like.

ORDER: CONIFERALES

Leaves persistent, small, scale like, usually in rows or whorled, bract scale fuses with the ovuliferous scale pollen grains not winged.

FAMILY: CUPRESSACEAE

Leaves scale like, usually arranged in 4 ranks of 2 opposite sets, foliage glandular and aromatic, female cone ovoid to oblong, cone scale with thickened or ridged apex a fine spine, seed small, thin, attached to the edge of the scale.

GENUS: THUJA

6. Juniperus:

Vegetative Structure:

Plants are evergreen shrubs or trees. The stem is branched and branchlets are covered by two types of leaves – acicular and scaly and are in rows. The plants have thin bark and at maturity some bark is scaled off in longitudinal strips. The wood is fragrant, mostly coloured (reddish or reddish brown) and very durable.

Reproductive Structure:

The plants may be monoecious or diocidus.

Male Strobilus:

It is composed of numerous microsporophyll’s arranged on a central axis. Each microsporophyll has ovate or peltate scale-like connective and bears 2-6 globose sporangia (pollen sacs). Pollen grains are not winged.

Female Strobilus:

It is surrounded at the base by minute scale like bracts, which persist unchanged under the fruit or cone. It also contains 3-8 opposite or ternate, pointed and united scales. It is fleshy and becomes berry like bearing one or more seeds. Bract scale is fused with ovuliferous scale (Fig 7.10).

Identification:

Plants branched trees or shrubs, leaves simple, microphyllous, wood well developed.

CLASS: CONIFEROPSIDA

Plants evergreen, stem with secondary wood and resin canals, strobilus compact and cone like.

ORDER: CONIFERALES

Leaves persistent, small, acicular and scale like, usually in rows, bract scale fused with the ovuliferous scales, pollen grains not winged.

FAMILY: CUPRESSACEAE

Leaves of two types-acicular and scale like, arranged in rows, female cone fleshy, berry like, containing single or several seeds.

GENUS: JUNIPERUS

7. Cryptomeria:

Vegetative Structure:

Plants are evergreen, branched trees; branches are usually in whorls, horizontal or drooping. Leaves are spirally arranged, persistent, awl-shaped, and 0.6 – 1.5 cm long. The bark of mature plant is reddish-brown in colour, fibrous, becoming detached in long shreds.

Reproductive Structure:

Male and female strobili arc borne on different parts of the same branch. In each strobilus fertile scales and bracts are distinct.

Male Strobilus:

It is sub-terminal and borne in clusters of 20 or more from the leaf axils. It is about 0.6 to 1.6 cm long, and orange or reddish in colour at maturity. It is composed of several microsporophyll’s bearing microsporangia. Pollen grains are not winged.

Female Strobilus:

It is developed on short branchlets, appearing as small green rosettes of leaves. Mature cones are brownish, globular, solitary, 1.5 – 2 cm in length and breadth. Each cone has 20 – 30 ovuliferous scales, centrally attached on the axis.

The scales are straight or curved, and having spine like processes at the apex. Seeds are dark brown, and irregularly triangular with “rudimentary wings. A peculiarity of these taxa is that the growing shoot is sometimes prolonged from the apex of the female cone. (Fig 7.11).

Identification:

Plants branched trees, leaves simple, microphyllous, wood well developed.

CLASS: CONIFEROPSIDA

Plants evergreen, stem with massive secondary wood and resin canals, strobilus compact and cone like.

ORDER: CONIFERALES

Leaves spirally arranged, ovuliferous scale and bract free when young and extensively united when mature, ovules 2 to 9 per ovuliferous scale, pollen sacs 2 to 9 per microsporophyll, pollen grains wingless.

FAMILY: TAXODIACEAE

Leaves persistent, fertile scale and bract distinct, growing shoot prolonged from the apex of the female cone.

GENUS: CRYPTOMERIA

8. Podocarpus:

Vegetative Structure:

Plants are mostly branched evergreen trees. The branches are whorled or irregular. Leaves are very variable, dense or distant on the branches, spirally arranged, rarely opposite or sub-opposite in 2 close ranks or crowded and overlapping, varying in size from mere scale like bodies to a length of 20 – 25 cm and a width of 5 cm. Leaves are thin and fragile or thick and leathery with recurved margins.

Leaves are lanceolate in shape. In T.S. through the leaves, it shows that both epidermises have stomata and there is presence of conspicuous transfusion tissue on either side of the vascular bundles. Transfusioi tissues are composed of pitted sclerosis and fibres, which are arranged mostly perpendicular to the vascular bundles.

Reproductive Structure:

Plants are dioecious.

Male Strobilus:

It is cylindrical, and borne on lateral branches forming dense, narrow catkins. There are two pollen sacs per microsporophyll. Pollen-grains are with 2 or 3 wings.

Female Strobilus:

It is stalked or sessile, axillary or terminal with usually 2-4 scales, one or two of which bear in their axils a fertile scale folded over and united to an inverted ovule – usually one only matures. The sterile scales are often fused with the upper part of the stalk and develop a swollen, fleshy, brightly coloured, edible receptacle on which the seed is borne (Fig 7.12).

Identification:

Plants branched trees, leaves single, microphyllous, wood well developed.

CLASS: CONIFEROPSIDA

Plants evergreen, stem with pro­nounced secondary wood and resin canal, strobilus compact and cone like.

ORDER: CONIFERALES

Leaves are mostly lanceolate, spirally arranged, pollen-sacs two per microsporophyll, pollen grains with 2-3 wings, ovules erect or reflexed.

FAMILY: PODOCARPACEAE

Leaves with conspicuous transfusion tissues on both sides of vascular bundles, male strobilus borne in catkins, in female strobilus the sterile scales often fusing with the upper part of the stalk and produce a swollen, fleshy, edible receptacle on which seed is borne.

GENUS: PODOCARPUS

9. Taxus:

Vegetative Structure:

Plants are densely branched evergreen trees. The branches are spreading, and covered by brownish scales. Leaves are spirally arranged, spreading all rounds in erect shoots but appearing more or less 2-ranked on horizontal shoots. Leaves are simple, linear, 1 – 4 cm long, convex and shining on the upper side, with recurved margins. There is a prominent midrib and tapering apex.

Stem Anatomy:

In T.S. of stem, there is conspicuous absence of resin ducts and wood parenchyma. The medullary rays are uniseriate and the tracheids of secondary wood have spiral thickenings as well as uniseriate bordered pits.

Leaf Anatomy:

In T.S., leaves show two layers of cutinised epidermis, lower epidermis with sunken stomata, mesophyll cell zone (upper pallisade and lower spongy parenchyma), a vascular bundle surrounded by bundle sheath and transfusion tissue.

Reproductive Structure:

Plants are dioecious. The male flowers are organised into strobili but the female flowers are solitary.

Male Strobilus:

It is stalked, globose and arising from the axils of the leaves on the undersides of the branches of the previous year. Each consists of a short axis, bearing about a dozen spirally arranged scales at the base and a cluster of tightly packed umbellate micro-sporophylls at the top. Each microsporophyll is a peltate and shield shaped body, having 6-8 pendant microsporangia.

Female Strobilus:

It is solitary, green and developed from the leaf axils. The primary axis contains a number of overlapping sterile scale leaves at the base. A fertile shoot (secondary axis) is born in the axil of the uppermost scale leaf and it consists of three pairs of minute decussate scale leaves. The secondary axis ends in a single ovule. Seed erect with a bony shell, borne in a scarlet fleshy cup or aril. (Fig 7.13).

Identification:

Plants branched trees, leaves simple, microphyllous, wood well formed.

CLASS: CONIFEROPSIDA

Plants evergreen, stem with secondary wood.

ORDER: CONIFERALES

Leaves spirally arranged, resin canals absent in wood, tracheids with uniseriate pits, ovule one and arillate, micro-sporangiophore peltate or scale like, pollen sacs 2 to 8.

FAMILY: TAXACEAE

Leaves simple, dorsiventral, with transfusion tissue, male strobilus bears clusters of tightly packed umbellate micro-sporophylls at the top, ovule erect, terminal and arillate.

GENUS: TAXUS

10. Cephalotaxus:

Vegetative Structure:

Plants are evergreen branched shrubs or trees. The branching pattern is opposite or whorled, young branchlets are green, prominently grooved and marked with minute white stomatic dots.

Leaves are spirally arranged and spreading on vertical shoots; on lateral shoots they are arranged in two opposite ranks. Leaves are scarcely stalked, linear and pointed at the apex. The upper surface of the leaf is dark shining green with a conspicuous midrib, lower surface with a broad silvery band composed of numerous stomatic lines.

Reproductive Structure:

Male and female strobili are developed on different trees or rarely on the same tree.

Male Strobilus:

It is globose and formed in the axils of the upper leaves. It consists of groups of several stamens or microsporophyll’s enclosed by a bract. Pollen sacs are two in each microsporophyll. Pollen grains are wingless.

Female Strobilus:

It is stalked, only a few in number. It is composed of opposite pairs of cup-shaped bracts with 2 ovules at the base of each bract. Usually only one of the ovules develops into an olive like ‘fruit’/seed.

Seed:

It consists of a fleshy outer covering and an inner, woody, a corn shaped shell enclosing the kernel (endosperm) and embryo (with two cotyledons) (Fig 7.14).

Identification:

Plants branched trees, leaves simple and microphyllous, wood present.

CLASS: CONIFEROPSIDA

Plants evergreen, stem with secondary wood, male and female flowers cone like.

ORDER: CONIFERALES

Leaves opposite or whorled on branches, dioecious, male flower in globose heads, pollen grains wingless, female flowers pedunculate, ovules two each on ovuliferous scale but one develops into an olive like ‘fruit’/seed.

FAMILY: CEPHALOTAXACEAE

Leaves linear, pointed at the apex, upper surface of leaf dark shining green with a conspicuous midrib, lower surface with a broad silvery band composed of numerous stomatic lines.

GENUS: CEPHALOTAXUS.

11. Picea:

Vegetative Structure:

Plants are medium size to tall branched evergreen trees. The branches are whorled and usually small, but branchlets are slender and their surface roughened by prominent, persistent peg like projections (pulvini) left by the fallen leaves. Leaves are needle like, angled or flattened, persisting for several years. The anatomy of stem and leaf, as examined, are identical with that of the genus Pinus.

Reproductive Structure:

Male and female strobili appear on different branches of the same tree in the leaf axils of the previous year’s shoots.

Male Strobilus:

It is ovoid to cylindrical, erect or drooping, yellow or crimson in colour. It is composed of numerous spirally arranged micro-sporophylls (stamens). Pollen sacs are attached in pairs on the ventral surface of the microsporophyll’s. Pollen grains are mostly winged.

Female Strobilus:

It arises from the ends of the shoots, violet or purple in colour when growing. It is composed of numerous pointed or rounded scales bearing-2 ovules at the base of each. Cones are pendulous, cigar shaped and 6 – 15 cm. long. After the seed is shed the cones ripen for some time on the trees. The ovuliferous scales are persistent, with crenate, entire or lobed margins free from bract scale. Seeds are small, with well-developed wings (Fig 7.15).

Identification:

Plants branched shrubs/trees, leaves simple and microphyllous, wood formed.

CLASS: CONIFEROPSIDA

Plants evergreen, stem with conspicuous secondary wood, resin canals present, male and female strobili cone like, compact.

ORDER: CONIFERALES

Leaves linear to needle shaped. Ovuliferous scale free from bract scale, ovules two on each scale, pollen grains winged.

FAMILY: PINACEAE

Branchlets slender, their surface roughened by prominent persistent peg like projections left by the fallen leaves, strobili drooping, woody, persistent, cigar shaped, 6-15 cm. long, seed winged.

GENUS: PICEA

12. Araucaria:

Vegetative Structure:

Plants are branched evergreen trees. The branching pattern is horizontal or in whorls. Leaves are persistent for many years, and spirally arranged. They are also clasping with the stem and overlapping or thrown into 2 or more ranks by means of a basal twist.

Each leaf is mostly lanceo­late, flat, up to 5 cm. long, leathery and sharply pointed. But there are wide variations in the size and shape of leaves on different parts of the same tree. Bark resinous, ridged, rough, peeling off as papery scales.

Reproductive Structure:

Male and female strobili are usually borne on different trees, but sometimes on different branches of the same tree.

Male Strobilus:

It is dense and cylindrical, solitary or in clusters at the points of the branches, or from axillary buds. It consists of many spirally arranged micro-sporophylls (stamens). Pollen – sacs are five to fifteen. Pollen grains are wingless.

Female Strobilus:

It is woody, globose or ovoid with closely overlapping scales which fall off when mature. Seeds are one on cach scale and adherent to it, winged on each edge, scales completely united with sporophylls (Fig 7.16).

Identification:

Plants branched trees, leaves simple and microphyllous, wood well formed.

CLASS: CONIFEROPSIDA

Plants evergreen, stem with secondary wood and resin duct. Strobili compact cone like.

ORDER: CONIFERALES

Leaves large and spirally arranged, scales completely united with sporophylls, Ovules one per scale and reflexed. Pollen grains not winged.

FAMILY: ARAUCARIACEAE

Leaves persistent, spirally arranged, clasping the stem and overlapping, male strobili dense and cylindrical, female strobili woody, globose or ovoid, seeds one on each scale and adherent to it, winged on each edge.

GENUS: ARAUCARIA

13. Cedrus:

Vegetative Structure:

Plants are evergreen branched trees. Branchlets are of two kinds – long terminal shoots, bearing scattered leaves and short spur shoots which bear tufts of leaves in false whorls. Leaves are needle like, persistent, lasting 3-6 years, usually 3 sided.

Internally leaves have almost identical features of Pinus leaf, except the presence of 2 marginal resin canals on the inner surface. The bark of young trees are greyish, thin and smooth, at length becoming brown, thick, deeply furrowed and broken into small irregular plates.

Reproductive Structure:

Male and female strobili are borne on the same or on separate trees. Strobili are solitary and erect on the short shoots.

Male Strobilus:

It is stiff, erect, cylindrical, catkin like and up to 7 cm long and 1 – 1.5 cm. wide. It consists of numerous densely crowded anthers which open longitudinally. Pollen grains are wingless.

Female Strobilus:

It is small, greenish, about 1.5 cm. long and 0.5 cm. in diameter in young stage. Cones arc larger, and woody at maturity and composed of several woody bract scales which arc closely overlapping, fan shaped with a basal stalk like claw. Seeds – 2, attached to each ovuliferous scale. Each seed has a broad membranous apical wing several times larger than the seed. (Fig 7.17).

Identification:

Plants branched trees, leaves simple and microphyllous, wood well developed.

CLASS: CONIFEROPSIDA

Plants evergreen, stem with secondary wood and resin canals, strobili compact, and cone like.

ORDER: CONIFERALES

Leaves needle like, arranged in tufts on young branches, plants mostly monoecious, cones woody, ovuliferous scale free from bract scale.

FAMILY: PINACEAE

Cones are erect, leave on short spur shoots in tufts, leaves persistent, pollen grain wingless, ovuliferous scale with two seeds, seed having broad membranous wings.

GENUS: CEDRUS

14. Abies:

Vegetative Structure:

Plants arc evergreen branched trees. Branches arc more or less regularly whorled. Leaves are arranged on the branchlets in various ways – spreading all-round the shoot or crowded and directed forward in overlapping ranks.

Leaves arc dark green, glaucous, linear, short pointed and waxy. Internally leaves have a few stomata on upper surface and also 2 resin ducts which are marginal. The foliage persists form several years and after leaf shedding, a disc like scar develops on the shoot. The bark of young trees is smooth or beset with resin blisters, but in old trees deeply furrowed at the base.

Reproductive Structure:

Male and female strobili are borne on the same tree.

Male Strobilus:

It is short, catkin like and develops from the leaf axils on the underside of the branchlets which, on falling, leave gall-like scars. It is composed of several microsporophyll’s. Pollen grains arc winged.

Female Strobilus:

It is composed of numerous woody bracts, each bearing a large scale with 2 ovules at the base. Mature cone is erect and situated on the upper branchlets with closely overlapping, fan shaped scales and hidden or protruding bracts. The scales and bracts fall off as soon as the seeds arc ripe and the persistent axis remain on the tree. Seeds are winged. (Fig 7.18).

Identification:

Plants branched trees, leaves simple and microphyllous, wood well developed.

CLASS: CONIFEROPSIDA

Plants evergreen, stem with secondary wood, resin canals present in stem and leaf, strobili compact cone like.

ORDER: CONIFERALES

Leaves linear, crowded on stem, each ovuliferous scale has a pair of seeds, pollen grain winged.

FAMILY: PINACEAE

Cones erect, scales shedding off leaving a central axis on the tree.

GENUS: ABIES

15. Ephedra:

Vegetative Structure:

Plants are straggling woody shrubs or climbers with characteristic jointed, fistular and green stems. Branching is poor. Leaves are very small, scaly, usually opposite decussate. Each scaly leaf shows a thick midrib with a thin border which very rarely shows any stoma.

Stem Anatomy:

In T.S. through the young stem, the following tissue layers are noticed − a cuticularised epidermis composed of thick walled cells, hypodermis, and sunken stomata in the furrows, chlorenchymatous cortex, an endodermis; conjoint, collateral open vascular bundles arranged in ring and large central pith composed of thick-walled cells (Fig 7.19).

Reproductive Structure:

Plants are mostly dioecious but rarely monoecious. Both male and female flowers/or strobili are borne on separate clusters called “inflorescences”.

Male Strobilus:

It is borne in whorls in the axils of scale leaves at each node of the fertile branch. Each strobilus consists of a short axis bearing 2-8 opposite decussate pairs of bracts. Of the bracts the lower one or two pairs are sterile while all the upper bracts bear solitary flowers in their axils. Each flower contains a pair of bracts called perianth, a stalk called microsporophyll and 2 to 8 microsporangia at the tip of microsporophyll. Microsporangia contain several microspores or pollens.

Female Strobilus:

It is formed in the same manner as the male strobilus. In this strobilus most of the lower pairs of bracts are sterile, and there are two female flowers in the axils of the uppermost pair of bracts. Each mature female strobilus has one ovule surrounded by a 2 layered integument.

Ovule:

A mature ovule has a pair of bracts, two layers of integument, nucellus which is free from integument, except at the base, and a large megaspore. Pollen chamber is somewhat conspicuous. There is a vascular supply at the base of the ovule. (Fig 7.20).

Identification:

Strobili – inflorescence like, leaves opposite decussate, stem devoid of resin canals, embryo dicotyledonous, micropylar tube extremely long.

CLASS: CHLAMYDOSPERMOPSIDA

Leaves are scaly and opposite, stem chlorophyllous and with ridges and furrows, stomata present on the stem and leaf surface, haplocheilic type.

ORDER: EPHEDRALES

Both strobili compound, lower bracts mostly sterile.

FAMILY: EPIIEDRACEAE

Inner integument extended from the ovule and thus forming a long micropyle, pollen chamber conspicuous, male strobilus solitary but female strobili borne in pair.

GENUS: EPHEDRA

16. Gnetum:

Vegetative Structure:

Plants are woody lianas type. There are two types of branches – branches of unlimited growth (long shoots) and branches of limited growth (short shoots). The nodes of the long shoots are articulated and swollen mostly. Leaves are borne on the dwarf shoots. Leaves are large, oval, entire, reticulately veined, petriolate, dorsiventrally flattened, dicotyledonous type. They are borne in opposite decussate pairs.

Stem Anatomy:

T.S. through the stem shows dicot stem like features, i.e., there is presence of a single layered cuticularised epidermis, with sunken stomata; collenchymatous hypodermis; large cortex, an endodermis, pith and endarch vascular bundles arranged in a ring.

Each bundle is conjoint, collateral and open; xylem possesses vessels and phloem possesses sclerotic cells. In some species there is conspicuous secondary growth, both extrastelar and intrastelar. Periderm is thin and devoid of lenticels. (Fig 7.21).

Leaf Anatomy:

T.S. of leaf shows two layers of epidermis with stomata on the lower epidermis only, conspicuous palisade and spongy mesophyll cells, mixed with sclerotic cells, and closed vascular bundles surrounded by bundle sheaths.

Reproductive Structure:

Plants are dioecious. Both male and female strobili are formed in compound structures called inflorescences in the axils of leaves or in terminal positions of dwarf shoots.

Male Strobilus:

Each strobilus develops in the axil of a bract or apically on a dwarf shoot. It shows a slender axis with a pair of concrescent bracts at its base and higher up, each node of the axis bears opposite decussate bracts which are connate throughout their whole length.

In the axils of these connate bracts (called collars), the male strobilus is located. Each male strobilus consists of a stalk with two unilocular anthers or microsporangia and a sheathing perianth which is apparently formed by the fusion of two bracteoles. Each microsporangium bears many microspores or pollens.

Female Strobilus:

It is also spike like and develops from the same position as the male strobilus. At maturity a few female strobili develop and peep out of the connate bracts. Each female strobilus contains one large conspicuous ovule and a pair of perianth.

Ovule:

There is a two layered integument just outside the nucellus. Al the centre there is a prominent female gametophyte without archegonia and pollen chamber. Each ovule is covered by perianth. Micropylar tube is conspicuous. There are three separate vascular traces entering perianth, outer integument and nucellus zone. (Fig 7.22).

Identification:

Leaves are opposite decussate, stem devoid of resin canals, strobili inflorescence like, embryo dicotyledonous, micropylar tube extremely long.

CLASS: CHLAMYDOSPERMOPSIDA

Leaves are large, dorsiventrally flattened, reticulately veined like dicotyledons; stomata of syndetocheilic type.

ORDER: GNETALES

Plants woody lianas type, anatomically stem and leaf are just like those of dicotyledons, male and female strobili spike like, presence of vessels in the xylem tissue.

FAMILY: GNETACEAE

Female gametophyte devoid of archegonia and pollen chamber, presence of sclerotic cells in leaf mesophyll.

GENUS: GNETUM