638 MISC. PUBLICATION 4 2 3, U. S. DEPT. OF AGRICULTURE 

 1. MYRIOPHYLLUM. Watermilfoil 



Submersed leaves (often all of the leaves) pinnately dissected into 

 capillary divisions; flowers axillary or in interrupted terminal spikes, 

 often emersed; petals present or absent; stamens 4 or more; fruit 

 4-celled, deeply 4-lobed. 



Key to the species 



1. Leaves all alike, in whorls of 4 to 6, pinnatifid, the segments linear- filiform, 

 not more than 5 mm. long; flowers axillary 1. M. brasiliense. 



1. Leaves dimorphic, the submersed ones in whorls of 3 or 4, pinnate, the segments 

 capillary, commonly at least 10 mm. long, the emersed (floral) leaves bract- 

 like, entire or merely dentate, not or but slightly surpassing the flowers; 

 flowers in interrupted terminal spikes 2. M. exalbescens. 



1. Myriophyllum brasiliense Cambess. in A. St. Hil., Fl. Bras. Merid. 



2: 252. 1829. 



Myriophyllum proserpinacoides Gill, ex Hook, and Arn. in 

 Hook., Bot. Misc. 3: 313. 1833. 



In a pond near Sacaton, Pinal County (Peebles 10607), apparently 

 well established, perhaps introduced by migrating wild fowl. Native 

 of South America. Parrotfeather. Commonly grown in aquaria and 

 ponds. 



2. Myriophyllum exalbescens Fernald, Rhodora 21: 120. 1919. 



Myriophyllum spicatum L. var. exalbescens Jepson, Man. Fl. 

 PL Calif. 691. 1925. 



Apache, Navajo, and Coconino Counties, 6,200 to 9,000 feet, ponds 

 and lakes, June. Canada to Florida, northern Arizona, and Cali- 

 fornia. 



2. HIPPURIS. Marestail 



Stems usually partly emersed, erect, not branched; leaves all 

 simple, entire, in whorls of 6 or more; calyx not lobed, almost com- 

 pletely adnate to the ovary; petals none; style filiform, in a groove 

 formed by the lobes of the single anther. 



1. Hippuris vulgaris L., Sp. PL 4. 1753. 



Marsh Lake, White Mountains, Apache County, 9,000 feet (Gold- 

 man 2450). Widely distributed in the cooler parts of the Northern 

 Hemisphere. 



90. ARALIACEAE. Ginseng family 

 1. ARALIA 



Plants perennial, herbaceous or shrubby; leaves large, compound, 

 with large leaflets; flower small, regular, perfect or unisexual, in 

 umbels, these forming terminal panicles; calyx adnate to the ovary; 

 petals and stamens 5 each, borne on the calyx; fruit berrylike, several- 

 seeded. 



The underground parts are more or less spicy-aromatic. The roots 

 of a North American species and an Asiatic species of a related 

 genus, Panax, commonly known as ginseng, are highly esteemed for 

 medicinal purposes in China. 



