HYDROCHARIDACEJE. (FROG'S-BIT FAMILY.) 495 



Tribe I. STRATIOTIDE^l. Ovary 6- 9-celled : stigmas 6-9, 



1. Xiimuobium. Filaments 6-12, unequally united in the sterile flowers : anthers linear. 

 Tribe II. YALLISIVERIEiE. Ovary 1-celled with 3 parietal placentae: stigmas 8. 



2. A n a char is. Stem leafy. Tube of the perianth of the fertile flowers thread-form. 



3. Vallisneria. Stemless. Tube of the perianth not prolonged beyond the ovary. 



1. LIMNOBIUM, Richard. American Frog's-bit. 



Flowers dioecious, (or monoecious?) 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 (ovules ortho- 

 tropous, Torr.). — A stemless perennial herb, floating in stagnant water, pro- 

 liferous by runners, with long-petioled and round-heart-shaped leaves, which 

 are spongy-reticulated and purplish underneath ; rootlets slender, hairy. Ster- 

 ile flowers rather small ; the fertile larger ; peduncle nodding in fruit. Petals 

 white? (Name from \ip.vo(3ios, living in pools.) 



1. L. Sp6ngia, Richard. (Hydrocharis Spongia, Bosc. H. cordifolia, 

 Nutt.) — Lake Ontario (Dr. Bradley, Dr. Sartwell), Illinois, Dr. Vasey, and in 

 the Southern States. Aug. — Leaves 1'- 2' long, faintly 5-nerved. Peduncle 

 of the sterile flower about 3' long, thread-like; of the fertile, only I', stout. 



2. ANACHARIS (and Elodea), Richard. Water-weed. 



Flowers polygamo-dicecious, solitary and sessile from a sessile and tubular 2- 

 cleft axillary spathe. Sterile flowers small or minute; with 3 sepals, barely 

 united at the base, and usually 3 similar or narrower petals : filaments short and 

 monadelphous at the base, or none; anthers 3-9, oval. Fertile flowers either 

 pistillate or apparently perfect : perianth extended into an extremely long and 

 capillary tube; the limb 6-parted ; the small lobes (sepals and petals) obovate, 

 spreading. Stamens 3-9, sometimes merely short sterile filaments, without 

 anthers, or with imperfect ones, sometimes with oblong anthers Ovary 1-celled, 

 with 3 parietal placentas, 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 herbs, grow- 

 ing under water, with elongated branching stems, thickly beset with pellucid 

 and veinless, 1-nerved, sessile, whorled or opposite leaves. The staminate flow- 

 ers (which are 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, which are raised to the surface by the excessively prolonged calyx- 

 tube, varying in length according to the depth of the water. (Name formed of 

 cu>, throughout, and adapts, without charms, being rather homely water- weeds.) 



1. A. Canadensis, Planchon. Leaves in threes or fours, or the lower 

 opposite, varying from linear to oval-oblong, minutely serrulate ; stamens 9 in 



