MEMOIRS FROM THE DEPARTMENT OF BOTANY OF COLUMBIA COLLEGE. 25 



7. SUBGENUS DURAVIA. 



Suffrutescent or suffruticose, very slender and glabrous plants, annual or perennial 

 by a woody rootstock. Stem generally erect, rarely decumbent with erect branches, 

 wiry, more or less branched, strict or flexuous, usually clothed with a dark brown or 

 reddish, shining bark. Leaves narrow and inconspicuous, somewhat coriaceous or fleshy, 

 reduced to bracts towards the ends of the branches and branchlets, not articulated to the 

 ocreae, with two more or less prominent ribs, developed along the margins. Ocreae 

 funnelform, soon much lacerate as a rule, the segments bristle-like, rigid, soft or cottony, 

 contiguous and imbricated on the branches and branchlets, more or less distant on the 

 stems. Calyx sessile, rather colored, five-parted, mostly hidden in the ocreae. Stamens 

 usually eight, included. Style three-parted, appearing as the summit of the ovary or 

 achene spht into three segments, the segments more or less divergent. Achene trique- 

 trous, chestnut-colored or brown, smooth and shining or granular and dull. Albumen 

 horny. Cotyledons incumbent. 



KEY TO THE SPECIES. 



Plant perennial, with a branched base. 

 Plants annual, with simple bases. 



Ocreae conspicuouslj'^ lacerate, mostly distant, the segments rather weak. 



Ocreae conspicuously lacerate, mostlj' imbricated, the segments verjr rigid. 



Ocreae conspicuously lacerate, the segments cottony. 



Ocreae twO-parted, the segments ovate, sharply toothed. 



8. SUBGENUS TINIARIA. 



Herbaceous or suffruticose plants, glabrous, pubescent or more or less scurfy, annual 

 or perennial, unarmed. Stem erect and woody or extensively twining and soft, more or 

 less channeled. Leaves membranous or coriaceous, cordate, hastate or sometimes sagit- 

 tate, petioled or sessile. Ocreae funnelform, oblique, naked or fringed at the summit or 

 base. Inflorescence axillary or terminal, racemose or paniculate, more or less compound, 

 the ultimate divisions being racemes. Racemes loosely flowered, leafy, leafy-bracted or 

 naked. Calyx membranous, green, white or yellowish, five-parted, the three outer seg- 

 ments naked, keeled or strongly and conspicuously winged, borne on slender, reflexed 

 and articulated pedicels. Stamens eight, included. Style three-parted, short or almost 

 wanting, the three-cleft stigma nearly sessile. Achene triquetrous, dark brown or black, 

 included, smooth and shining or granular and dull. Albumen horny. Cotyledons 

 accumbent. 



