PITCHER-PLANT.

139

freshed by a single shower, produces water-melons, each of which weighs from fifty to seventy pounds.*

It has been, before, mentioned that the cucullate leaves of the Sarracenia genus contain water. The latter is, most probably, secreted into the hollow leaf by the vessels of the plant itself, and not, as in the Tillandsia, deposited by the rains. The species belonging to the genus grow in swampy grounds, and therefore, a provision for storing-up moisture against dry weather would be superfluous; besides, the leaf is surmounted by a lid, which would prevent the intrusion of rain. These circumstances strengthen the conclusion, that the object of the fluid in the leaves of the Sarracenia is to entrap insects. But the most extraordinary receptacle of water hitherto discovered in the vegetable kingdom, is the appendage to the leaf of the Pitcherplant (Nepenthes distillatoria). This species is a native of Ceylon and Amboyna; its leaves are lanceolate; and beyond the apex of each, the midrib protrudes, like a tendril, to the length of five or six inches. The extremity of this tendril bears the peculiar cup, or pitcher, from which the plant is named. Fig. 44. It is cylindrical, about six inches Fig. 44.

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long, and one and a half in diameter, and contains several ounces of

by a lid.*

very pure water. Its top is closed

The water is, unquestionably, secreted by the vessels of the plant: insects creep into it under the lid, and are drowned, except a small species of shrimp, which, according to Rumphius, lives in it. "I have no doubt," Sir J. E. Smith observes, "that this shrimp feeds on the other insects and worms, and that the same purposes are answered in this instance, as in the Sarraceniæ." +

The pitcher-plant is common about Columbo, the British capital of Ceylon, where it is called monkey-cup; for it is said that the monkeys, when thirsty, seek it out, and drink its contents. ‡

87. FOLIA demersa, immersa, or submersa, leaves growing under water; emersa, protruding above the surface of water; natantia, floating.

Many plants grow completely submerged in water, and die in any other situation. Various circumstances, however, besides the bare immersion, are requisite for different species. Thus, some delight in stagnant ponds; others in clear lakes; some in slowly flowing brooks, and others are only found in the rapid stream of mountain rivulets. Seaplants, too, are in general of a very different description from those of the fresh waters. With some exceptions, plants which grow in water emerge

* Cordiner's Ceylon, vol. i. p. 382.
+ Intr. to Botany, p. 175.

Maria Graham's Journal, p. 105.

FLOATING LEAVES.

141

from its surface, to produce their flowers and seeds in air; and sometimes there is a very great dissimilarity between the immerged and emerged leaves of the same plant. We have a striking example of this in the water-crowfoot (Ranunculus aquatilis), a species common in pools. Some of its leaves are submerged, others floating; the latter are broad, trilobed, and subpeltate; the former divided into many filaments, almost as fine as hairs.

The water-lily, the pondweed, the duckmeat, and a great many other plants, have leaves which float on the surface. Such leaves afford resting places, especially on their under-surfaces, for many aquatic insects, and their larvæ; and for helices and other fresh-water shells; and sometimes they serve as floating rafts for certain birds which prey on fish and other inhabitants of the water. In birds of the Parra genus, the toes and nails are of a most extraordinary length, the intention of which seems

to be to enable the bird to walk over floating leaves. Labillardiere saw the Chinese Jacana (Parra Sinensis) walking on the Nymphæa Nelumbo, and he admired, he says, "the lightness with which it walked over the surface of the water, stepping with its long legs from one leaf to another.” *

COMPOUND LEAVES.

These consist of two or more leaves on one petiole, and several of them, as the digitate and pedate leaves, have been already described.

88. FOLIUM binatum, a binate leaf.

89. FOLIUM conjugatum, a conjugate or yoked leaf. The binate is a species of digitate leaf, and consists of two leaflets arising from the extremity of one footstalk. Fig. 45. (a) But if a footstalk, in place of terminating in two leaflets, have them on its sides, then it forms a conjugate leaf. Fig. 45. (b) The only difference, therefore, between a binate and a conjugate leaf is, that in the former the petiole terminates in two leaflets; in the latter these spring from its sides; for the one is a digitate, the other a pinnate leaf. Though thus different, however, they are in general used synonymously.

If the petiole divide at the summit, and each division end in two leaflets, it is a bigeminate leaf, FOLIUM bigeminatum (bis, twice, and gemini, twins, Lat.). Fig. 45. (c) And if such a petiole have two leaflets at its division also, it forms a trigeminate leaf. Fig. 45. (d)

*Voyage, vol. ii. p. 327.

The conjugate leaf, as we have just seen, has one pair of leaflets on the petiole; but some plants have two pairs, forming a bijugous leaf, FOLIUM bijugum (bis, twice, and jugum, a yoke or pair, Lat.), and some three, forming a trijugous leaf, &c.

90. FOLIUM ternatum, a ternate leaf, when one petiole has three leaflets, as in strawberry and trefoil. 91. FOLIUM biternatum, twice ternate.

92. FOLIUM triternatum, thrice ternate.

Let us, for the sake of illustrating the biternate and the triternate leaf, have recourse to a well known object, the pawnbroker's sign. This may be called ternate, having three balls, as the strawberry leaf has three leaflets. But suppose the branch or foot-stalk of each ball to be again split into three, and each of these to be armed with a ball, then the balls will be nine, and the object will be biternate, as it has formed a second division into threes.

Suppose again each branch of this second or biternate division to be farther split into three, then the balls will amount to twenty-seven, and the object will be triternate, having formed a third