Pandan Straws.
Description of Pandans.
Pandans or “screw-pines,” as they are sometimes called, are readily recognized by their characteristic appearance.[5] The common forms occasionally planted in pots as house plants and in gardens, or more often found growing wild, have long and rather narrow leaves always supplied with more or less sharp spines which run along both their margins to the very tip. Another row of spines is present on the under surface along the midrib. Bearing in mind this middle row of spines it is impossible to mistake the leaf of the pandan for that of the pineapple or maguey, which it resembles more or less in form and shape. Another very prominent feature of pandans is the presence of air or prop roots which grow from the stem above the ground and are helpful to the plant in various ways. The veins of the leaves always run parallel and in a longitudinal direction. The leaves are never borne on a petiole, but are attached directly, in winding corkscrew fashion, in ranks of three, to the stem.
Pandans are true tropical shrubs or trees. Although also found in the subtropics of Australia, they never occur in other temperate regions except when raised as ornamental plants in greenhouses. Even their distribution in the tropics is limited, as they are found growing wild only in the tropical regions of the Old World, especially on the islands lying between the mainland of Australia and southeastern Asia. They are hardly ever cultivated, for where they do occur they are found in more than sufficient quantity for the purposes to which they are put. They are essentially seacoast or open swamp forms, generally found at low altitudes and appearing to find a moist, warm climate most congenial to their growth. In the Philippines they occur in all provinces, though not always in sufficient quantity to make them of commercial importance.
The structure of the pandans presents many exceedingly interesting characteristics well worth noticing. Some plants are very low with leaves not wider than a blade of grass, while others form large trees with leaves many meters long and several decimeters wide. Spines generally occur along the whole margin of the leaf, though in a few forms, especially in cultivated varieties, they may be present only at the tip or may be wanting entirely. The marginal spines usually curve forward and vary in size from small, hardly perceptible forms, to large sharp conical structures. At times they are set very close together; again they may be several centimeters apart. Those on the midrib most often curve backwards and may vary the same as the marginal spines. Generally the spines are green in color, though in some species they are pale-green, red, black or white.
Some forms seem to creep along the ground, while others, low and bushy and standing close together, form, with their numerous supporting prop roots, an almost impenetrable jungle. The high tree forms are very striking because of their peculiarly shaped crowns.
The first roots which the pandans develop soon disappear and their place is taken by others. Starting high above the ground, these grow at an angle from the stem and generally reach the soil. They serve the twofold purpose of supporting the stem and of supplying it with sufficient air. If, by accident, the underground roots die off, the plant relies entirely on these air and prop roots for support and food. The strong prop roots are generally of the same diameter throughout, though sometimes they thicken at the ends. Normally they never branch above the ground, but after reaching the soil very often divide. The tip of the roots is protected by a cap, while a layer of cork tissue prevents the drying out of the root body.
The pandan has two kinds of flowers, male and female. The male flowers are arranged in the form of a spike protected by a modified leaf called the bract. They are white in color, crowded together on the spike and consist of stamens which hold the pollen. The flowers do not have the showy colored bracts which forms so prominent a feature in those of many other plants. The female flowers consist only of the necessary parts. As the pollen occurs in enormous quantities and as the plants generally grow in groups, it is very probable that some flowers are pollinated by the wind. The fact that many pandans have very fragrant blossoms makes it almost certain that in the majority of cases insect pollination takes place. In a few forms that have a very disagreeable odor, pollination is effected by night flying insects.
The fruit commonly has the general shape of the female inflorescence, but as it matures it increases greatly in size. Pandans have a composite fruit made up of smaller fruits called drupes. The most common forms resemble the pineapple with its leafy fruit apex cut off. As is natural, variations from this type occur. Cylindrical, eggshaped, jackfruit-like forms are quite common. The largest may be 60 cm. long and weigh 25 kilos, the smallest only 7 cm. in length and 60 grams in weight. The fruit may occur solitary at the end of a branch, or in groups. The color is green, though some species change to a bright red before maturity is reached. The fruit may have drupes ranging from 12 mm. to 14 mm. in length and these may contain one seed or a number of seeds. At maturity the drupes separate and the fruit falls apart. If the plant occurs along the water, the seeds, when liberated, float about until they rest in a suitable place for germination.