254 HALORAGIDACEAE. 



335. HIPPURIS. 



Perennial herbs, with simple erect stems and whorled simple 

 entire leaves; flowers small, perfect or polygamous; calyx entire; 

 style thread-shaped with the stigma on one side lying in a groove 

 between the lobes of the single large anther; fruit nut-like, 1- 

 celled, 1 -seeded. 



Leaves 8-12 in each whorl; tall aquatic plant. H. vulgaris. 



Leaves 5-6 in each whorl; minute alpine plant. H. montana. 



Hippuris vulgaris L. Mare's Tail. Aquatic; stems simple, 30-90 cm. 

 high; leaves usually 2-4 cm. long, linear, acute, in whorls of 6-12, rather rigid 

 or the submersed ones flaccid. 



Borders of lakes and ponds, not common. 



Hippuris montana Ledeb. Terrestrial; stems 2-8 cm. high; leaves in whorls 

 of 5 or 6, 8-12 mm. long. 



In wet places in alpine meadows, often forming extensive colonies. 



336. MYRIOPHYLLUM. WATER MILFOIL. 



Perennial aquatics; leaves crowded, often whorled; submersed 

 ones pinnately parted into capillary lobes; flowers monoecious or 

 polygamous, sessile in the axils of the upper leaves, usually above 

 water; calyx of the staminate flowers 4-parted, of the fertile 

 4- toothed; petals 4 or none; stamens 4 or 8; fruit nut-like, 4-celled, 

 deeply 4-lobed. 



Stamens 4; petals persistent; floral leaves linear, sparingly 



denticulate. M. hippuroides. 



Stamens 8; petals deciduous. 



Floral leaves ovate, entire or toothed, shorter than the 



flowers. M. spicatum. 



Floral leaves pinnatifid, much longer than the flowers. M. verticillatum. 



Myriophyllum hippuroides Nutt. Lower leaves pinnate, the divisions 

 filiform; upper linear, acute, remotely dentate or nearly entire; petals white, 

 obovate; fruit 2 mm. long. 



In ponds, rare. 



Myriophyllum spicatum L. Leaves 2-3 cm. long, rather rigid, pinnately 

 parted into filiform segments, the rachis equally narrow; bracts ovate, entire 

 or dentate, about equalling the flowers; petals greenish. 



In lakes and ponds, not rare. 



Myriophyllum verticillatum pectinatum Wallr. Leaves flaccid, all dissected 

 into filiform segments; rachis flattened and broader than the segments; bracts 

 pinnatifid, shorter than or barely exceeding the flowers. 



In quiet lakes, infrequent. In typical M. verticillatum L., not known 

 from our limits, the bracts are much longer than the flowers. 



Family 71. ARALIACEAE. GINSENG FAMILY. 



Perennial herbs, shrubs, or trees; leaves simple or compound, 

 with dilated petioles; flowers umbellate, paniculate or racemose; 



