670 VALLISNERIACEvE PHILOTRJA 



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 GUI 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 3-1'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 PHILOTR1A Kaf. 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-dioecious, 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^3 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 monoaciousar 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- 

 e h aped and membranaceous in staminate: style with 2-4 subu /ate 

 stigmas 



