MACLOSKIE: COMPOSITE. 80 1 



HETEROTHALAMUS TENELLUS ROBUSTIOR. 

 S. Patagon., St. Julian. 

 "Our plants are all males." (H. & A.) 



21. BACCHARIS Linn. 



Shrubs or herbs, with dicecious, discoid, small or mid-sized heads, 

 female in the fertile plants, hermaphrodite in the sterile. Anthers basi- 

 obtuse. Achenes compressed, usually 5-io-costate. Pappus-seta copious, 

 i to several-seriate, fewer and tortuose in the sterile flowers. 



(Fig. in Eng. & Prantl, iv, 5, p. 171.) 



Species 300, chiefly in trop. Amer.; some in U. S.; in W. Indies. Of 

 many only one sex is known ; consequently the specific characters are 

 derived chiefly from the leaves. Young leaves and twigs frequently 

 bearing glandular hairs which produce a colorless secretion. (Volkens.) 



KEY TO THE SPECIES. 

 A. Branches 3 -winged. 



b. Leaves reduced to acute scales. Interrupted spikes. trimera. 



b2. Glabrous. 



c. Leaves elliptic-ovate. Achenes costate. chubutensis. 



cz. Leaves minute, subternate scales. Heads i-many spicate. Achenes sulcate. 



genistelloides. 



3. Leaves linear-lanceolate. Heads spicate. sagittalis, 



A2. Branchlets angular. 

 b. Glabrous. 



c. Leaves fan-shaped, toothed, viscid when young. Heads axillary, crowded. 



flabellata. 



c2. Leaves linear, toothed. Heads crowded at ends of branches. denticulata. 



CT,. Leaves obovate-oblong, a tooth on each shoulder. Heads crowded, conferta. 

 c4. Branches leafy. Leaves linear-attenuate. Heads solitary. gilliesii. 



b2. Glabrous-viscid. 



c. Leaves obovate-cuneate, subentire, evergreen. Heads solitary, sessile on ends of 



branches. magellanica. 



C2. Leaves ovate-cuneate, rugose, toothed. Pedicels axillary, i -headed. (Viscid when 



y un g-) patagonica. 



CT,. Leaves cuneate, tridentate. Female heads axillary. microphylla. 



*4. Young branches striate-angulate. Leaves oblong-cuneate, apically toothed, narrower 



upwards. Spicate heads. platensis. 



3. Puberulous. Leaves remote, linear, entire. Heads solitary on corymbed branches. 



darwinii. 

 A$. Branchlets terete. 



b. Puberulous at first, then glabrous-viscid. Leaves linear, toothed. Heads many, terminal. 



confertifolia. 



