ONAXGRACB^. 117 



flowers, often monoecious or dia'cious. Calyx-tube not at 

 all prolonged, the lobes obsolete or none. Petals 8 to 4, 

 often none. Stamens 1 to 8. Otary inferior, 1 to 4-celled. 

 Fruit dry, indehiscent, 1 to 4-celled. Seeds pendulous, I 

 in each cell. 



PROSERPINACA. Linn. Mermaid-weed. 



Lat. proserpo, to creepy the steins creeping and rooting at the base. 



Calyx-tube 3-sided, limb 3-parted. Petals none. Sta- 

 mens 3. Stigmas 3. Fruit long, 3-angled, 3-celled, 

 3-seeded, nut-like. — Low perennial aquatic herbs, with the 

 stems creeping at the base, alternate leaves, and small fertile 

 flowers sessile in the axils, solitary or 3 or 4 together. 



1. P. palustris, L. Common Mermaid-weed. 



Upper leaves linear-laneeolate, serrate: lower ones often pinnatifid; fruit sharply 

 3-angled. 



Wet swamps ; rare. July, Aug. Stem 12 to 18 inches long, roundish. Leaves 

 about 1 inch Ion;*, *4 wide, acute at each end, lower ones, on short petioles, if sub- 

 merged pinnatifid with linear segments like the teeth of a comb. Flowers greenish, 

 tessile, 1 to 3 together. Stigmas purple, cylindrical. 



2. P. pectinacea, Lam. Cut-leaved Mermaid-weed. 



Leaves all pectinate, the divisions linear-awl-shaped; fruit rather obtusely 

 3-angled. 



Sandy swamps ; rare. Aug. Stems 5 to 15 inches high, ascending at base from 

 long creeping roots. Leaves all regularly and finely divided into very narrow 

 tegmenta like the teeth of a comb. Styles none. Stigmas attenuate above. 



MYRIOPHYLLUM. Vaill. Water Milfoil. 



Or. anurias, a myriad, phullon, a leaf; from the numerous divisions of the leaf 



Flowers monoecious or polygamous. Calyx of the 

 sterile flowers 4-parted, of the fertile 4-toothed. Petals 

 4, or none. Stamens 4 to 8. Fruit nut-like, 4-celled, 

 deeply 4-lobed. Stigmas 4, recurved. — Submersed aquatic 

 perennial herbs, with crowded often whorled leaves, those im- 

 mersed pinnately parted into capillary divisions, and sessile 

 flowers in the axils of the upper leaves: upper ones staminate. 



* Stamins S; petals deciduous; leaves whorled in threes. 



1. M. spicatum, L. Spiked Water Milfoil. 



Leaves all pinnately parted and capillary ; Jloral ones or bracts shorter than the 

 flowers, ovate entire; lower ones sub-serrate and larger; petals broadly ovate; 

 stamens 8. 



In water. Aug., Sept. Stem slender, branched, varying in length with the 

 depth of the water, the flowers only rising above the surface. Leaves composed of 

 innumerable, hair-like segments. Fkwers greenish sessile. Carpels smooth. 



