Читать книгу Cucurbits - James R. Myers - Страница 17

Fruit of the Cucurbitaceae are extremely diverse in many characteristics, including size, shape, colour and ornamentation. Those of bryony are small (ca 5 mm), spherical, and green, red or black in rind colour. Angled luffas are club-shaped, about 60 cm long, and prominently ribbed. Some of the many shapes of bottle gourds are described in Chapter 4. The striped, mottled, bicoloured or solid-coloured fruit of squash are smooth, wrinkled, warted, furrowed or ridged. Sicyos has stiff, dry spines, whereas those on the teasel gourd are soft and fleshy.

Cucurbita maxima is well named, for it is this species that is the giant of the plant kingdom. Every year, there is a contest to grow the world’s largest pumpkin. In this contest any squash fruit with an orange skin is considered a pumpkin, and the winners are invariably C. maxima. Weights crossed the 500 kg threshold in 1999 and the 1000 kg threshold in 2014. The winning fruit in 2016 weighed an astounding 1193 kg. Giant watermelon contests are also run, with the winning fruit in 2015 weighing 137 kg.

Cucurbit fruit are generally indehiscent ‘pepos’, usually with one or three ovary sections or locules (Fig. 1.2). A pepo is a fleshy fruit with a leathery, non-septate rind derived from an inferior ovary. However, fruit of some cucurbit genera, e.g. Momordica and Cyclanthera, split at maturity. Fruit of squirting cucumber forcefully eject their seeds through a blossom-end pore. Fruit may be dry when mature, as in luffa, where seeds fall out through a hole at the bottom of the pendulous fruit. Mature fruit of many cucurbits have a hard, lignified rind, but various squash cultivars have been bred to have a tender rind.

Fig. 1.2. Frontal and cross section of female flower from Cucurbita pepo (spaghetti squash).

Cucurbit fruit flesh is generally white to pale yellow and moist, but cultivated cucurbits such as melon, squash and watermelon have been bred to have a range of flesh colours. Melon and squash have also been bred to include green or orange flesh, and watermelon flesh can be white, salmon yellow, canary yellow, orange, coral red or scarlet red. In melon, watermelon and squash, the flesh is derived from the fruit wall. In other species, including cucumber, the edible flesh may be mostly placental in origin.

Many cultivated cucurbits produce a fleshy fruit at maturity. Others, such as gourd and luffa, dry at maturation. When a luffa fruit matures and dries, what is left is a papery outer skin and a fibrous mass surrounding the seeds. This tangled mass of modified vascular bundles, consisting mostly of fibre cells, makes up a luffa sponge.