Part 160 (1/2)

_Aquatic herbs, with dicious or polygamous regular flowers, sessile or on scape-like peduncles from a spathe, and simple or double floral envelopes, which in the fertile flowers are united into a tube and coherent with the 1--3-celled ovary._ Stamens 3--12, distinct or monadelphous; anthers 2-celled. Stigmas 3 or 6. Fruit ripening under water, indehiscent, many-seeded. Seeds ascending, without alb.u.men; embryo straight.

Tribe I. HYDRILLEae. Stem elongated, submerged, leafy. Spathes small, sessile.

1. Elodea. Leaves verticillate (rarely opposite). Perianth-tube long-filiform.

Tribe II. VALLISNERIEae. Stemless. Leaves elongated. Spathes pedunculate.

2. Vallisneria. Submerged; gra.s.s-like. Fertile flower solitary on a very long scape.

Tribe III. STRATIOTEae. Stem very short, with crowded leaves. Spathes pedunculate. Ovary 6--9-celled.

3. Limn.o.bium. Stemless, floating; broad leaves long-petioled.

1. ELODeA, Michx. WATER-WEED.

Flowers polygamo-dicious, solitary and sessile from a sessile tubular 2-cleft axillary spathe. Sterile flowers small or minute, with 3 sepals barely united at base, and usually 3 similar or narrower petals; filaments short and united at base, or none; anthers 3--9, oval. Fertile flowers pistillate or apparently perfect; perianth extended into an extremely long capillary tube; the limb 6-parted; the small lobes obovate, spreading. Stamens 3--9, often with imperfect anthers or none.

Ovary 1-celled, with 3 parietal placentae, each bearing a few orthotropous ovules; the capillary style coherent with the tube of the perianth; stigmas 3, large, 2-lobed or notched, exserted. Fruit oblong, coriaceous, few-seeded.--Perennial slender submerged herbs, with elongated branching stems, thickly beset with pellucid and veinless, 1-nerved, sessile, whorled or opposite leaves. The staminate flowers (rarely seen) commonly break off, as in Vallisneria, and float on the surface, where they expand and shed their pollen around the stigmas of the fertile flowers, raised to the surface by the prolonged calyx-tube, which varies in length according to the depth of the water. (Name from ???d??, _marshy_.)

1. E. Canadensis, Michx. Leaves in 3's or 4's, or the lower opposite, varying from linear to oval-oblong, minutely serrulate; stamens 9 in the sterile flowers, 3 or 6 almost sessile anthers in the fertile.

(Anacharis Canadensis, _Planchon._)--Slow streams and ponds, common.

July.

2. VALLISNeRIA, L. TAPE-GRa.s.s. EEL-GRa.s.s.

Flowers strictly dicious; the sterile numerous and crowded in a head on a conical receptacle, enclosed in an ovate at length 3-valved spathe which is borne on a very short scape; stamens mostly 3. Fertile flowers solitary and sessile in a tubular spathe upon an exceedingly lengthened scape. Perianth (calyx) 3-parted in the sterile flowers; in the fertile with a linear tube coherent with the 1-celled ovary, but not extended beyond it, 3-lobed (the lobes obovate); also 3 linear small petals.

Stigmas 3, large, nearly sessile, 2-lobed. Ovules very numerous, scattered over the walls, orthotropous. Fruit elongated, cylindrical, berry-like.--Stemless plants, with long linear gra.s.s-like leaves, wholly submerged. The staminate cl.u.s.ters being confined to the bottom by the shortness of the scape, the flower-buds themselves break from their short pedicels and float on the surface, where they shed their pollen around the fertile flowers, which are raised to the surface by sudden growth at the same time; afterwards the thread-form scapes (2--4 feet long) coil up spirally, drawing the fruit under water to ripen. (Named for _Ant. Vallisneri_, an early Italian botanist.)

1. V. spiralis, L. Leaves linear, thin, long and ribbon-like (1--6 long), obscurely serrulate, obtuse, somewhat nerved and netted-veined.--Common in slow waters, N. Eng. to Fla., west to Minn.

and Tex.

3. LIMNBIUM, Richard. AMERICAN FROG'S-BIT.

Flowers dicious, (or moncious?) from sessile or somewhat peduncled spathes; the sterile spathe 1-leaved, producing about 3 long-pedicelled flowers; the fertile 2-leaved, with a single short-pedicelled flower.

Calyx 3-parted or cleft; sepals oblong-oval. Petals 3, oblong-linear.

Filaments entirely united in a central solid column, bearing 6--12 linear anthers at unequal heights; there are 3--6 awl-shaped rudiments of stamens in the fertile flowers. Ovary 6--9-celled, with as many placentae in the axis, forming an ovoid many-seeded berry in fruit; stigmas as many as the cells, but 2-parted, awl-shaped.--A stemless perennial herb, floating in stagnant water, proliferous by runners, with long-petioled and round-heart shaped leaves, which are spongy-reticulated and purplish underneath; rootlets slender, hairy.

Sterile flowers rather small; the fertile larger; peduncle nodding in fruit. Petals white? (Name from ???????, _living in pools_.)

1. L. Spongia, Richard. Leaves 1--2' long, faintly 5-nerved; peduncle of sterile flower about 3' long and filiform, of the fertile only 1' long and stout.--Stagnant water, N. J. to Fla.; also L. Ontario, Ill., and Mo.

ORDER 109. BURMANNIaCEae. (BURMANNIA FAMILY.)

_Small annual herbs, often with minute and scale-like leaves, or those at the root gra.s.s-like; the flowers perfect, with a 6-cleft corolla-like perianth, the tube of which adheres to the 1-celled or 3-celled ovary; stamens 3 and distinct, opposite the inner divisions of the perianth; capsule many-seeded, the seeds very minute._--A small, chiefly tropical family.

1. BURMaNNIA, L.