322 PICKEREL-WEED FAMILY. 



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

 the 1-celled 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, FROG'S-BIT. (Name in Greek means living in 

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



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

 of Lake Ontario: rooting copiously; leaves l'-2 f long, purple beneath, tuniid 

 at base with spongy air-cells. 



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

 destitute of charms.) Fl. summer, ^f 



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

 long branching steins, beset with pairs or whorls of pellucid and vcinless 

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

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

 inches long. 



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

 (Named for A. Vatlisneri, an early Italian botanist.) Fl. late summer. ^ 

 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 cyclosis. (See Structural Botany, p. 31, 

 Lessons, p. 167.) 



116. PONTEDERIACE^, PICKEREL-WEED F. 



A few water plants, distinguished from the foregoing by having 

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

 ers perfect. Represented by 



Schbllera graminea, or WATER STAR-GRASS ; 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. 



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. limosa, in mud S. W. : distinguished by its oblong or lance-oblong 

 leave?, and solitary blue flower. The only widely common plant of the family 

 belongs to 



1. PONTEDERIA, 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 forming an tipper 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 fruit. Stamens 6, the 3 lower in the throat, with incurved fila- 

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

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

 P. COrdata, COMMON P. Everywhere in shallow water; stem l-2high, 



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



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



a conspicuous yellowish-green spot: fl. all summer. 2* 



