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Cucurbitaceae are climbing or procumbent herbs, annual or perennial, with extra-axillary simple or branched tendrils; monoecious or dioecious; stem usually 5-angled. Leaves are simple, alternate, palmiveined and palmilobed or rarely pinnately veined and lobed; exstipulate.
Inflorescence racemose or cytnose or flowers solitary. Flowers are unisexual, regular, pentamerous, epigynous, usually large, yellow or white. Calyx more or less tubular, lobes 5, imbricate or open in bud. Corolla inserted on the calyx tube, gamopetalous, campanulate or rotate; lobes 5, imbricate or induplicate-valvate: rarely corolla lobes free almost to the base or very rarely completely free.
Stamens 5 in male flowers but usually appearing 3 as filaments of 4 stamens unite in pairs; lilamenis usually coherent and often fused and monadelphous; anthers all unithecal and synandrous; anther lobes sigmoid or convolute or conduplicate, exirorse.
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In female (lowers ovary tricarpellary, syncarpous, inferior, 3-celled with ∞ ovules on axile placentation; ovules anatropous with 2 integuments; style short and thick usually divided in 3 stigmatic branches: stigmas thick, often horse-shoe shaped.
Fruit usually a pepo with tough or hard pericarp, dehiscent or indehiscent, often opening by a hole at the apex; sometimes of great size. Seeds without endosperm and with a large embryo; cotyledons oily. Dendrosicyos is a soft wooded tree of Socotra Island.
Acanthosicyos is a thorny leafless shrub of S. Africa with a branched greatly swollen tap root running to a length of about 15 m. Ecballium a trailing or prostrate herb of the Mediterranean region is without tendril. Bisexual flowers occur in Schizopepon. The petals are free in Fevillia, Luffa, Lagenaria, etc. In Fevillia there are 5 free stamens.
Four other types of androecium are met with viz:
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(1) Filaments of 4 stamens coherent below in 2 pairs, the 5th remaining free;
(2) The coherent filaments unite completely so that the andoecium seems to be made up of 3 stamens, 2 with 2-celled anthers and one with 1-celled anther,
(3) Filaments free below and united above or completely united and the anthers all united and spirally twisted,
(4) Stamens completely united with the lobes of the anthers forming 2 horizontal rings surrounding a peltate mass of connectives.
The first type is exemplified in Thladiantha, the second type is met with in Bryonia, Citrullus, Momordica, etc., the third type in Cucurbita, and in Cyclanthera the fourth type is found.
Difference of opinion exists regarding the true nature of the placentation and the ovary being unilocular or trilocular. Engler, Eichler, Wettstein and Willis considered that the ovary was trilocular, the carpels intruding and meeting at the centre and the placentation was axile.
Rendle and others are of the opinion that the ovary is unilocular and the placentation is parietal, the placentas growing inside and meeting at the centre often filling the cavity of the ovary cell. Sicyos and Seehium have a sloitary ovule and the seed of Sechium germinates viviparously.
The fleshy fruit of Momordica splits into 3 parts and the seeds are ejected. Luffa has a dry fruit with a fibrous network of vascular bundles. The fruit opens by an aperture at the apex through which the seeds come out.
The fruit of Ecballium gets detached when fully ripe and the seeds together with the watery fluid that it contains are ejected violently through the aperture at the base of the fruit. The fruit of Lagenaria has a hard pericarp which when breaks due to some external pressure the seeds come out. In other cases the seeds are released when the fruit rots.
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The seeds are smooth but in some genera corrugated or sculptured. In Zanonia the seeds are winged. Regarding the morphological nature of the tendril different hypothesis have been put forward. Engler’s view is that the tendril is a modification of the stipule. Of a pair of lateral stipules one is suppressed while the other is transformed into a tendril.
Kedrostis spinosa Med. seems to be a good example of this. Naudin considered the tendril to be an axillary branch the axis of which was united with the main stem and the tendrilar portion represented the midrib of a reduced leaf.
Payer expressed the view that the tendril resulted due to the splitting of the petiole. According to Braun and Wydler the tendril is a modified bracteole which is displaced from its original position. This view is supported by Eichler.
The widely accepted view however is that of Muller who stated that the tendril was a metamorphosed branch, the lower thick portion representing the axis and the upper coiled portion representing the leaf.
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This view is based on different transitional forms of the tendril of Cucurbita pepo DC. where the upper portion often becomes flattened and winged like a leaf blade. Hagerup supported Muller’s hypothesis.
Floral formula for male and female are expressed as:
Cystoliths are present in the epidermal cells of the leaves. The vascular bundles are arranged in 2 rows. These are bicollateral with 2 strands of fascicular cambium and 2 patches of phloem. The vessels and sieve tubes are very large. Perforations are simple. The st0mata are Ranunculaceous.
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The family consists of about 100 genera and 350 species, distributed in the tropical and subtropical countries- and a few species occurring also in the temperate regions. Some are found in very humid areas while quite a fair number inhabit the arid zones.
In India about 90 species are found many of which are cultivated. Of the wild plants Trichosanthes bracteata (Lamk.) Voigt.—Makal, T. cucumerina Linn.—Banchichinga, Coccinia grandis (L.) Voigt.—Telakucha, Momordica cochinchinensis (Lour.) SprengKakrol, Zehneria umbellata Thw.—Kudari, etc. are very common in the plains.
Many are cultivated for the luscious fruits, viz. Citrullus Janatus (Thunb.) Mak. Tarbuz (Water melon), Cucumis melo Linn.—Kharbuz, Phunti, Sarda, etc. (Melon), C. sativus Linn. Sosha, Khira (Cucumber), etc.
As vegetables most important are, — Trichosanthes dioica Roxb.—Palwal, T. nnguina Linn.—Chichinga (Snake gourd), Benincasa hispida Cogn.—Chal Kumra, Petha (Wax gourd), Lagenaria leucantha (Duch.) Rusby, Louki (Bottle gourd), Momordica charantia Linn.—Karela (Bitter gourd), Luffa cylindrica (L.) Roem.—Dhundul, Ghia Toroi (Bath sponge), L. acatangula (L.) Roxb.—Jhinga, Kali Toroi, etc.
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Cucurbita maxima Duchesne—Mitha Kadu, Mitha Kumra (Gourd, Spanish gourd) originally of Africa, C. pepo DC.—Kumra, Safed Kadu (Pumpkin) originally of S. America and C. moschata Duchesne—Safra Kumra (Musk melon) originally of S. America are widely cultivated. Sechium edule Linn.—Chocho or Chyota also of S. America is much cultivated in Darjeeling and Shillong.
Tender shoots of many of the above species are also used as pot herbs. A few have medicinal properties, e.g. the stem and leaves of Trichosanthes dioica are much used by Indian Kabirajes as febrifuge, stomachic and for killing worms.
Citrullus colocynthis Schrad, has extremely bitter fruits, the pulp of which is purgative and with sugar given in dropsy and is applied in discoloration of skin. Different species of Bryonia also possess medicinal properties.
Pax and Muller divided the family into 5 subfamilies as noted below:
Group A:
Anther lobes not united in a ring.
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Subf. I Fevilleae:
Stamens 5, rarely 4; free or united only at base.
Subf. II Melothrieaes:
Stamens 5 but apparently 3, rarely 2 or 4; anther lobes usually straight.
Subf. III Cucurbiteae:
Stamens 5 but apparently 3; anther lobes sigmoid.
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Subf. IV Sicyoideae:
Stamens united in a column.
Group B:
Antherlobes united in a ring.
Subf. V Cyclanthereae:
Stamens united in a column; anther lobes fused in 2 rings round the top of the staminal column.
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The family has recently been divided in a different manner into 3 tribes:
I. Cucumerineae:
Female flowers always solitary; ovules transversely placed rarely pendulous.
II. Orthospermeae:
Ovules not transverse, erect or ascending.
III. Zanonieae:
Female flowers-in racemes or panicle, never solitary: ovules pendulous. The affinity of the family is not very clear and difference of opinion exists among the taxonomists regarding the systematic position of Cucurbitaceae.
This is no doubt an advanced family, being predominandy herbaceous, having unisexual epigynous flowers, gamopetalous corolla, syilandrium formation of stamens often with curved anther lobes and also having bicollateral vascular bundles.
Engler therefore placed his monotypic order Cucurbitales between Rubiales and Campanuiatae and considered this family to be closely allied to Campanulaceae with gamopetalous corolla, open type- of calyx, more or less synandrium formation, epigynous ovary and bicollateral vascular bundles in some genera Eichler and Wettstein supported Engler.
Bentham and Hooker placed Cucurbitaceae in the cohort Passiflorales with Passifloraceae, Loasaceae, Begoniaceae, Datiscaceae, etc. Hallier considered that Cucurbitaceae was closely- allied to Begoniacee and Datiscaceae which belonged to the order Peponiferae and according to him this order was derived from Passifloraceae.
Rendle and Hutchinson more or less agreed with Hallier due to the following common characters, viz. — bitegmic ovule, persistent nucellus and extensive tapetal tissue. Free petals in Fevillea (Cucurbitaceae) however bring it closer to Passiflora.
Flower of Fevillea resembles those in Rosaceae to some extent and therefore Bessey considered that the order Loasales consisting of Loasaceae, Cucurbitaceae, Begoniaceae, Datiscaceae and Ancistrocladaceae originated from Rosales.
Takhtajan places only Cucurbitaceae in his Cucurbitales and the order is placed by him between Passiflorales and Begoniales. So according to Takhtajan Cucurbitaceae, is allied to Passifloraceae on one side and to Begoniaceae and Datiscaceae on another side.
Cronquist includes Cucurbitaceae in Violales a large order wherein are included Passifloraceae, Loasaceae, Turneraceae, Begoniaceae, Datiscaceae, Ancistrocladaceae, etc. Cronquist consideis Violales to be a natural taxon derived from Theales.
According to him all the families included in Violales arc related to each other although the order appears to be a heterogenous assemblage. It is therefore clear that most workers consider that Cucurbitaceae is related to Passifloraceae, Begoniaceae, Loasaceae and Datiscaceae.
