OF NORTH AMERICA. 31 



804. Upopion heterophylum R. Thaspium 

 atropurp. auct. Stem striate, radical leaves 

 simple cordate, stem leaves trifoliate, terminal 

 foliole cordate or ovate, lateral ovate obliqual, 

 all serrate ; flowers peduncled, male on longer 

 peduncles. — This is the original sp. known and 

 called Smyrnium atropurpureum by Lamark, 

 leaves uncial, stem bipedal. So much like Zizia 

 cordata in habits as to have often been mis- 

 taken for a variety of it. 



805. Upopion cordatum Raf. stem simple 

 angular, all the leaves simple cordate petiolate, 

 acute unequaly serrate ; umbel single naked, 

 flowers glomerate subsessile mostly fertile. — In 

 the Alleghany Mts. evidently a very distinct sp. 

 pedal, 3 radical leaves uncial, one lobate on the 

 sides, two stem leaves remote larger. — These 5 

 sp. offer a beautiful illustration of the forma- 

 tion of species by gradual deviations of forms, 

 from pinnate to single leaves. They have 

 nothing left in common but smoothness and ser- 

 rate leaves besides the flowers. 



806. ZiziA PARviFOLiA R. stcm virgate 

 grooved pubescent like the petiols, radical 

 leaves small cordate trilobe crenate, stem leaves 

 sessile trifoliate, folioles unequal ovatoblong 

 acute unequaly serrate, medial larger ; umbel- 

 ules pauciflore with unequal slender peduncles. 

 — Very distinct from Z^ cordata by pubescence 

 small leaves mostly half inch long only, stem 

 pedal, flowers polygamous yellow, seeds oval 

 with 3 prominent ribs. Found in the Allegha- 

 ny Mts. 



807. SiuMis (Sium) hetewophyla Raf. stem 

 simple fistulose costate, lower leaves on very 

 long petiols trifoliate, folioles ovate serrulate, 

 medial petiolate, middle leaves pinnate, 5 to 7 



