322 PICKEUEL-WEED FAMILY. 



extremely .long and slender scape : tube of the perianth not prolonged beyond 

 the 1-cefled ovary, with 3 obovate outer lobes (sepals) and 3 small inner 

 linear ones (petals), and no stamens. Ovules very numerous lining the walls. 

 Stigmas 3, sessile, 2-lobed. Fruit cylindrical, berry-like. 



1. LIMNOBIUM, FKOG'S-BIT. (Name in Greek means living in 

 pools.) riowers whitish, the fertile ones larger, in summer. ^ 



L. Spdngia. Floating free on still water S. & W. ; has been found in bays- 

 of Lake Ontario: rooting copiously; leaves l'-2Mong, pui-ple beneath, tumid 

 at base with spongy air-cells. 



2. ANACHARIS, WATEE-WEED. (Name from the Greek means 

 destitute of cha-nns.) El. summer. ^ 



A. Canadensis. Slow streams and ponds : a rather homely weed, with 

 long branching stems, beset with pairs or whorls of pellucid and veinless 

 1-nerved minutely serrulate sessile leaves (^'-1' long), varying from linear 

 to ovate-oblong, the thi-ead-like tube of the yellowish perianth often several 

 inches long. 



3. VALLISNERIA, TAPE-GRASS, EEL-GEASS of fresh water. 

 (Named for A. Vallisneri, an early Italian botanist.) El. late summer, y, 



V. spiralis. In clear ponds and slow streams, with bright green and grass- 

 like linear leaves (l°-2° long), delicately nerved and netted; fertile scapes 

 rising 2° - 4° long, according to the depth of the water, afterwards coiling up 

 spirally and drawing the fruit under water to ripen. — The leaves of this and 

 the preceding are excellent to show cydosis. (See Struetural Botany, p. 31, 

 Lessons, p. 167.) 



116. PONTEDERIACEiE, PICKEEEL^WEED F. 



A few water plants, distinguished from the foregoing by having 

 the tubular corolla-like perianth free from the ovary, and the flow- 

 era perfect. Kepres'ented by 



Sehollera graminea, or "Water Star-Gkass ; a grass-like weed grow- 

 ing under water in streams, with branching stems beset with linear-pellucid ses- 

 sile leaves ; the flower with a slender salver-form pale yellow perianth, of six 

 narrow equal divisions raised to the surface on a very slender tube, and only 3 

 stamens. 



Heterantb^ra renif6rmis, Mud-Plantain, in mud or. shallow water 

 S. & W. ; with floating round-kidney-shaped leaves on long petioles, and 3-5 

 ephemeral white flowers, from the sheathing base or side of a petiole; their per- 

 ianth salver-form, with a slender tube, bearing 6 nearly equal divisions and 3 

 dissimilar stamens, one with a greenish, two with yellow anthers. 



H. Iiin6sa, in mud S. & W. : distinguished by its oblong or lance-oblong 

 leaves, and solitary blue flower. — The only widely common plant of the family 

 belongs to 



1. PONTEDEEIA, PICKEREL-WEED. (For the Italian botanist 

 Pontedera. ) Flowers in a terminal spike. Perianth of 6 divisions irregularly 

 united below in a tube, the 3 most united fonning an upper lip of 3 lobes, the 

 others more spreading and with more or less separate or lightly cohering 

 claws forming the lower lip, open only for a day, rolling up from the apex 

 downwards as it closes ; the 6-ribbed base thickening, turning green, and en- 

 closing the frnit. Stamens 6, the 3 lower in the throat, \vith incurved fila- 

 ments ; the 3 upper lower down and shorter, often imperfect Ovary 3-cellcd, 

 2 cells empty, one with a hanging ovnle. Fruit a 1-celled 1-seeded utricle. 

 P. COrd^ta, Common P. Everywhere in shallow water ; stem 1°- 2° high, 



naked below, above bearing a single petioled heart-shaped and oblong or lancc- 



nrrow-shaped obtuse leaf, and a spike of purplish-blue flowers; upper lobe with 



a conspicuous yellowish-green spot; fl. all summer. 2/ 



