Cucurbita
pepo L.
Standardized Common
Name: Pumpkin
Family: Cucurbitaceae
Taxonomy: The term “pumpkin”
has no taxonomic meaning, and is at least occasionally applied to large,
thick-rinded fruits belonging to four species, including C. argyrosperma
Huber subsp. argyrosperma (also known as C. mixta Pang.), C.
maxima Duch., and C. moschata Poir. as well as C. pepo. Cucurbita
pepo subsp. pepo, the most common of the cultivated species,
encompasses a wide variety of fruits, including zucchini and summer and winter
squash varieties as well as many pumpkins. The thin-hulled Styrian Oil Pumpkin,
C. pepo subsp. pepo var. styriaca Grebenščikov, is
commonly used in the production of pumpkin oil.
Description: Annual vine,
prickly-stemmed, with twining tendrils at the base of some leaves. Leaves
alternate, long-petioled, erect, to 30 cm long and broad, palmately lobed,
prickly; base cordate; apex and apices of main lobes broadly acute; margins
wavy or toothed. Plants monoecious. Flowers unisexual, solitary in leaf axils,
long-pedicelled; calyx cup-shaped, bristly, green, 5-lobed; corolla
funnel-shaped with 5 erect to spreading lobes, yellow, to 10 cm long. Male
flowers with 3 stamens; filaments white, short, free below and fused above;
anthers forming a central column, 1–1.5 cm long, yellow, with convoluted
surface. Ovary of female flower inferior, 3–5-loculed; styles fused into short
column; stigmas 3, yellow, convoluted. Fruit a pepo, with leathery exocarp and thick
fleshy edible mesocarp; size and shape extremely variable, the largest
exceeding 100 kg in mass; color variable, ranging from green and white to
bright orange at maturity; peduncle in fruit strongly 5-angled; seeds numerous,
to 2.5 cm long, ovate, flattened, pale.
Parts
in Commerce:
Seeds
Identification: Most varieties of C.
pepo are thick-hulled, which is the primitive condition.
- (10–)15–25 mm
long, 7–14 mm broad
- Strongly
flattened
- Ovate with a
narrowed neck, the neck often curved to one side
- Conspicuous
smooth, rounded margin around edges; groove or ridge delimiting margin
visible on each side of seed
- Groove may be
brownish-tinged, but margin itself not darker than face of seed
- Scar at end of
neck perpendicular to neck, slightly angled, or rounded
- Surface cream to
tan throughout, smooth or with irregular wrinkles
- Seed coat easily
broken; interior of seed taken up by whitish embryo surrounded by thin
green layer
- Embryo edible,
with mild, nutlike flavor
C.
pepo
var. styriaca:
The Styrian oil pumpkin and other thin-hulled or so-called “hull-less”
varieties are used for oil production due to the increased yield and reduced
need for processing to remove hulls. In these seeds, two layers of the
multilayered seed coat are missing and others differentially developed,
resulting in a very different appearance:
- Dark green due
to thicker chlorenchyma and absence of covering layers
- Outermost layer
thin, clear and membranous, sometimes peeling
- Edges narrowed,
not covered by a rounded margin; instead, a fine pale ridge may be visible
running around edge of seed
Other
species of “pumpkin”:
The following features may be used to distinguish seeds of C. pepo from
seeds of other commonly cultivated edible species:
C. argyrosperma (variable, with some
or all of the following features):
- Typically
whitish, sometimes with silvery overtones (rarely golden)
- Margin may be
ridged or wavy; color gray or light brown, often darker than face of seed
- Thicker than C.
pepo, with both faces conspicuously convex and elevated above a narrow
margin, often large
- Surface of some
varieties may be irregularly cracked, revealing long, narrow epidermal
cells like closely packed hairs
C. maxima:
- Usually white,
sometimes smooth brown
- Thicker than C.
pepo, plump; sometimes over 25 mm long
- Scar at end of
neck strongly oblique, often entirely on one side of neck and slanting
backwards (not to be confused with an oblique appearance caused mostly by
a curve in the neck itself, which is found in all species)
C.
moschata:
- Margin brownish,
darker than face of seed, which is grayish or tan
- Under
magnification, margin usually has irregular surface, appearing wavy, corky
or stringy
References:
Bailey LH. The domesticated Cucurbitas—I. Gentes
Herbarium (The Kinds of Plants). 1929;2:62–115.
Merrick LC. Systematics and evolution of a
domesticated squash, Cucurbita argyrosperma, and its wild and weedy
relatives. In: Bates DM, Robinson RW, Jeffrey C, eds. Biology and
Utilization of the Cucurbitaceae. Ithaca, NY: Cornell University Press;
1990:77–95.
Merrick LC. Systematics, Evolution, and
Ethnobotany of a Domesticated Squash, Cucurbita argyrosperma. Ph.D.
Dissertation, Cornell University; 1991.
Russell P. Identification of the commonly cultivated
species of Cucurbita by means of seed characters. J Wash Acad Sci.
1924;14:265–269.
Singh D, Dathan ASR. Structure and development of
seed coat in Cucurbitaceae. VI. Seeds of Cucurbita. Phytomorphology.
1972 [publ. 1973];22:29–45.
Teppner H. Cucurbita pepo (Cucurbitaceae)—history,
seed coat types, thin coated seeds and their genetics. Phyton.
2000;40:1–42.
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