CUCURBITACEAE (Gourd Family)
Contributed by
David J. Bogler
Plants annual or
perennial vines (woody elsewhere), climbing or trailing with coiled tendrils
from the nodes, usually monoecious or dioecious. Stems often 5-angled, often
hollow between the nodes, usually hairy. Leaves alternate, often
long-petiolate, simple but palmately (rarely pinnately) lobed or divided,
lacking stipules. Inflorescences axillary, of solitary flowers or in clusters,
sometimes racemes or panicles, sometimes the staminate flowers more numerous
and positioned toward the stem tip, the pistillate flowers then fewer and
toward the stem midpoint and/or base. Flowers staminate or pistillate,
epigynous, with a hypanthium extending above the ovary as a tube. Calyces 5- or
6-lobed, sometimes deeply so, actinomorphic. Corollas 5- or 6-lobed, sometimes
deeply so and appearing as free petals, actinomorphic, bell-shaped,
saucer-shaped, or less commonly trumpet-shaped, usually yellow or white, those
of staminate and pistillate flowers sometimes appearing somewhat different.
Stamens 5, but often appearing fewer because of fusion of 1 or 2 pairs of
stamens (appearing as 3 stamens in all Missouri genera), attached at or toward
the base of the inner side of the hypanthium, the filaments sometimes fused
into a column, the anthers facing outward, attached at or toward the base of
the inner surface, sometimes fused, often bent or contorted, reduced to
staminodes in pistillate flowers. Pistils 1 per flower, of 3 fused carpels,
highly reduced or absent in staminate flowers. Ovary inferior (incompletely so
elsewhere), with 1 locule, the 2–5 areas of placentation parietal (1 terminal
placenta and 1 ovule in Sicyos). Style 1 per flower, the stigma 1- or
3-lobed, the lobes sometimes each shallowly 2-lobed. Ovules most commonly
numerous. Fruits berries, sometimes with a hardened or leathery rind (then
known as a pepo), less commonly dry and capsulelike, indehiscent or bursting
irregularly in Echinocystis. Seeds numerous, less commonly few or only
1, often somewhat flattened, the seed coat usually of several layers, the outer
layer sometimes fleshy. Ninety to 130 genera, 800–900 species, nearly
worldwide, but most diverse in tropical and subtropical regions.
All members of
the family are sensitive to frost. The cultivated species are annual vines that
die back each year, and the temperate species often are perennial vines with a
deep, usually massive rootstock. Cucurbitaceae generally are noted for their
vining habit, coiled tendrils, palmately lobed leaves, inferior ovaries,
imperfect flowers, and often large, berrylike fruits known as pepos. They are
further characterized by the presence of a very bitter class of tetracyclic
triterpenoids known as cucurbitacins. The family once was thought to be closely
related to the Passifloraceae because of their similar tendrils, inferior
ovaries, and parietal placentation, but now the Cucurbitaceae are thought to be
closer to the Begoniaceae, another family with inferior ovaries having deeply
intruding parietal placentae (Angiosperm Phylogeny Group, 1998; Judd et al.,
2002).
Many species of
Cucurbitaceae have been domesticated and are grown for food, as ornamentals, or
for use in handicrafts, including various kinds of melons, squashes, cucumbers,
and gourds. Some species of the genus Luffa Mill. are cultivated for the
network of fibers in their fruits that are dried, cleaned, shaped, and sold
commercially as sponges. Seeds from some of these domesticated taxa often wind
up in waste areas, where they germinate and persist for many years before
ultimately succumbing to competition, herbivory, freezing temperatures, or
disease. If the progenitors of the cultivated variety were adapted to local
conditions and disturbed habitats, the plants may become feral and occupy
habitats similar to those of their ancestors. In the St. Louis area, several
species of Cucurbita and Cucumis, described below, have been
found growing untended along railroads and in waste areas.
Coccinia
grandis (L.) J. Voigt.
(ivy gourd, scarlet gourd) is a dioecious species native to Africa, southern
Asia, and Malesia that is cultivated in its native range for its edible fruits
and young foliage. It is an aggressive invasive exotic in portions of Australia
and on a number of Pacific islands, including Hawaii. It also has been reported
sporadically as an introduction in Texas and Florida. This species was
discovered in 1996 growing in a fencerow near a motel in Clinton (Henry County)
by members of the Missouri Native Plant Society. It is not known whether the
plants encountered were planted deliberately as an ornamental or for food, or
whether the plants were a chance introduction. The species is a strong
perennial with a large, tuberous rootstock and rapidly growing stems. It has
unbranched tendrils, glabrous leaves, solitary or paired short-stalked flowers
with white corollas 15–20 mm long, and large, fleshy, bright red, ellipsoid to
ovoid fruits 2–5 cm long. For now, C. grandis has been excluded from
formal treatment in the flora, but it should be monitored for potential spread
in southern Missouri.