100 – II.2. SQUASHES, PUMPKINS, ZUCCHINIS, GOURDS (CURCURBITA SPECIES)
commonly cultivated group of cultivars at present. Like the previous group, the zucchini
group has a strong affinity with the vegetable marrow and its origin is also recent (19th
century). Its plants are generally semi-shrubby and its cylindrical fruit does not broaden
or broadens only slightly. It is eaten as a vegetable in the unripe state (see Annex 2.A2 for
information on horticultural types.) Taxonomically, the morphotypes “pumpkin”,
“vegetable marrow”, “cocozelle” and “zucchini” are subspecies pepo. Some authors have
categorised the morphotypes “Scallop”, “Acorn”, “Crookneck” and “Straightneck” as
subspecies ovifera (also known as C. pepo ssp. texana, see e.g. Paris et al., 2003);
however, this chapter, which is based on the nomenclature used by Lira, Andres and Nee
(1995) and Lira Saade, Eguiarte Fruns and Montes Hernández (2009) and Gong et al.
(2012), would group these morphotypes in C. pepo ssp. pepo. (Both groups are shown as
C. pepo L. in Table 2.1).
Because of their small, hard shells, ornamental gourds are typically thought of as a
distinct grouping within C. pepo. Isozymic evidence, however, shows this not to be true,
with cultivars having originated in both subspecies pepo and ovifera and possibly in
subspecies fraterna (Decker-Walters et al., 1993). What many of these cultivars do share
in common are characteristics often ascribed to free-living populations, e.g. tough
pericarps and bitter flesh, which ward off predation in the wild.
Reproductive biology
Cucurbita is a genus of dicotyledonous flowering plants in the family Cucurbitaceae.
The cultivated Cucurbita are annual plants, long running and climbing, or short and
bushy. The flowers are monoecious and numerous and very showy. Flowers open very
early in the morning, and the predominant pollinators of these flowers are bees. In the
Americas, the most efficient pollinators are the solitary bees of the genera Peponapis and
Xenoglossa (Hurd and Linsley, 1970, 1976, 1964; Hurd, Linsley and Whitaker, 1971), but
the flowers can also be pollinated by other bees such as the honey bee, Apis mellifera.
Fruits are of the pepo type: a berry with numerous seeds surrounded by a fleshy wall that
does not open at maturity. Production of flowers, fruits and seeds varies between species
(Quesada et al., 1991).
Reproductive organs
Flower
Unisexual flowers are characteristic of the Cucurbitaceae. The Cucurbita species are
primarily monoecious with both male and female flowers on the same plant (Whitaker
and Robinson, 1986; Lira, Andres and Nee, 1995; Rzedowski and Rzedowski, 2001),
although some varieties of C. foetidissima are gynomonoecious (Whitaker and Robinson,
1986).
Cucurbita flowers are large, gamopetalous with tubular-campanulated corollas, and
showy, with a cream coloured or light yellow or bright-yellow orange corolla. Flowers
grow from the axil of a leaf. Male flowers have column-like stamens, with free or more or
less connivent filaments, and the anthers are joined together forming a cylindrical or
narrowly pyramidal structure. Female flowers have an inferior ovary with numerous
horizontally positioned ovules, the styles are fused in almost their entire length or are
only shortly free in the apex; stigmas are large, fleshy or more or less sunken or
lobulated, and slight modifications can be seen in the structure of the perianth regarding
the staminate ones, mainly corresponding to differences in size of one or some of its parts
