OF NORTH AMERICA. 
SI 
804. Upopion heteropiiylum 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 S myrnium atropurpureum by Lamark, 
leaves uncial, stem bipedal. So much like Zizia 
cordata in habits as to have often been t 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. stem 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. 
— V ery 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. Si u mis (Sium) heterophyla Raf. stem 
simple fistulose costate, lower leaves on very 
long petiols trifoliate, folioles ovate serrulate, 
medial petiolate, middle leayes pinnate, 5 to 7 
