HEMIBACCHARIS, A NEW GENUS OF BACCHARIDINAE. 
By S. F. Brake, 
INTRODUCTION. 
The genus Paccharis L. is one of the dozen largest genera of As- 
teraceae, containing some 250 to 300 species, all of which are con- 
fined to America. The genus is characterized by its functionally 
dioecious habit, the pistillate plants bearing heads composed en- 
tirely of pistillate fertile flowers with filiform corollas and an ex- 
serted style, while the staminate bear heads composed of hermaph- 
rodite but sterile flowers with tubular 5-toothed corollas and entire 
or 2-branched styles. Several generic names, based chiefly on real 
or supposed distinctions in the number or form of the pappus 
bristles, were published for different species of the genus by some of 
the early authors, but all these are now universally referred to 
Baccharis, and the only other genera now recognized in the subtribe 
Baccharidinae are Heterothalamus Less. and Parastrephia Nutt.’ 
The former has polygamo-dioecious heads. the staminate, of her- 
maphrodite but sterile flowers, sometimes provided with pistillate 
outer flowers with minutely or broadly ligulate corollas, the pistil- 
late without admixture of hermaphrodite flowers and with the recep- 
tacle provided with pales which half include the flowers. 
A group of some 15 species, occurring from Mexico to Costa Rica, 
has long afforded difficulty to botanists. These species, of which 
Baccharis mucronata H. B. K., B. hirtella DC., and B. asperifolia 
Benth. are the best known, are perplexingly intermediate between 
Baccharis and Eschenbachia (Conyza of most authors, not L.). 
They are herbs or shrubs with the general habit of Baccharis, but are 
polygamo-dioecious. The staminate plants are indistinguishable 
from Baccharis, but the pistillate bear heads containing 1 to 15 her- 
maphrodite but sterile central flowers with regular tubular corollas. 
On this account Baccharis asperifolia Benth. was referred by Ben- 
’ Since this paper was turned in for printing, further investigations in regard 
to Nuttall’s genus Parastrephia have left little doubt that. as was suggested by 
O. Hoffmann in 1890, it was founded on abnormal specimens of a species of 
Lepidophyllum Cass., probably L. phylicaeforme (Meyen) Hieron. This genus 
belongs to the Astereae-Solidagininae, and has no close affinity to Baecharis. 
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