670 VALLISNERIACE.E philotria 



mately 5-10-nerved, each with a central cluster of 2-11 elongated rootlets. 

 Common in still water throughout most parts of the world. 



Order CIII VALLISNERIACE^E Dumort. Anal. Fam. 54. 



Submerged or floating aquatic herbs with various leaves and 

 regular mostly dioecious flowers. Perianth 3-6-parted: the 

 segments all petaloid, or the outer ones smaller and herbaceous, 

 the tube adherent to the ovary at its base. Stamens 3-l k J, dis- 

 tinct or monadelphous. Anthers 2-celled. Ovary 1-celled with 

 3 parietal placentae or 6-9-celled. Styles 3-9, with entire or 

 2-cleft stigmas. Fruit an indehiscent few-many-seeded utricle, 

 ripening under water. 



1 PHILOTRIA Raf. Am. Month. Mag. ii, 175. 



Aquatic perennial herbs with leafy branched stems, numerous 

 opposite or whorled sessile 1-nerved leaves and small flowers in 

 membranaceous spathes. Flowers poygamo-dicecious, solitary 

 and sessile in an axillary spathe. Perianth small in the stamin- 

 ate flowers with 3 scarcely united greenish sepals and as many 

 narrow petals: the pistillate with greatly elongated filiform tube 

 and 6- parted spreading limb. Stamens 3-9, with short filaments 

 united at base. Ovary 1-celled, with 3 parietal placentae, few- 

 ovuled. Style coherent with the perianth-tube: stigmas 3, bifid 

 or emarginate. Fruit a few-seeded utricle. 



P# Canadensis Britton Science (II) ii, 5. Anacharis Canadensis PL 

 Stems 4 inches to 3 feet long, according to the debth of the water, much 

 branched: leaves linear or elliptic, acute or obtuse, serrulate or entire, 2-7 

 lines long, 1-2 lines wide: flowers axillary, the staminate minute, sessile, 

 breaking off at the time of flowering and rising to the surface where they 

 shed their pollen : pistillate flowers expanding on the surface of the water 

 which they reach by the elongation of the slender tube which varies in 

 length from 2-12 inches : stigmas spreading, papillose or pubescent. Com- 

 mon in ponds, nearly throughout North America. 



Order CIV NAIADACE.E Lindl. Nat. Syst. ed. 2, 366. 



Aquatic herbs with slender often branching leafy stems, flat 

 or filiform leaves and perfect, monoecious or dioecious flowers 

 in axillary spikes or solitary or spadaceous. Perianth of 4 seg- 

 ments or a hyaline envelope or wanting. Stamens 1-4, rarely 

 more, distinct and hypogynous in the perfect flowers, solitary or 

 connate in the sterile. Anthers extrorse, 1- 2-celled. Ovaries 

 1- 6, distinct, or rarely connate, 1-celled, mostly 1-ovuled . Fruit 

 follicular or capsular or an indehiscent berry or utricle. Em- 

 bryo large, often curved. Albumen none. 



* Perianth membranaceous and cup-shaped or none. 



*- Flowers monoecious ar dioecious : ovary solitary, sessile : stamen 1. 



1 Naias Stems slender, with opposite or ternate leaves : flowers dioecious' 

 solitary or clustered, axillary: perianth none in pistillate flowers, cup- 

 ehaped and membranaceous in staminate: style with 2-4 subu /ate 

 stigmas 



