JONES. — A REVISION OF THE GENUS ZEXMENIA. 159 



San Luis Potosi: San Jose Pass, Pringle, no. 3002. This plant 

 seems to have no very close affinities with the other known species, but 

 in respect to the achenes it most nearly resembles Z. Pringlei. 



-t- h- Achenes winged. 

 ++ Squamellae minute or wanting. 



28. Z. Pringlei, Greenman. Tall, slender-branched, suffruticose or 

 fruticose, arachnoid-pubescent except on the upper surface of the leaves : 

 leaves opposite or the uppermost alternate, ovate, generally less than 3 cm. 

 long, subcordate at the base, obtuse or acute at the apex, above rugose 

 and appressed-tuberculate-hispid, beneath densely tomentose ; petioles 4 

 to 7 mm. long, narrowly margined : peduncles solitary, long, slender ; 

 heads 10 to 15 mm. high ; involucre 1 to 1.5 cm. broad, about 3-seriate and 

 subtended by several leaf-like bracts ; the inner scales oblong to oblong- 

 lanceolate : ligules oblong, about 12 mm. in length, usually half as broad : 

 achenes much as in the preceding species but slightly larger and those of 

 the ray-flowers verrucose, those of the disk-flowers winged. — Proc. Am. 

 Acad, xxxiii. 489 (1898). — Southern Mexico. Specimens examined, — 

 Puebla: near Tehuacan, alt. 2166 m., Pringle, no. 6768 (type, in herb. 



Gray). 



++ +*• Squamellae evident. 



29. Z. gnaphalioides, Gray. Slender-branched floccose-lanate 

 shrub: leaves deltoid-ovate to cordate-lanceolate, acute at the apex, entire, 

 revolute-margined, above shortly sericeous-hispidulous, beneath tomen- 

 tose; petioles very short: peduncles long, slender, solitary, tomentose or 

 floccose-lanate ; heads and involucre much as in the preceding but the sub- 

 tending foliaceous bracts much smaller : achenes short-necked, sparsely 

 pubescent, rugose; those of the ray-flowers 3 mm. long, narrow, with 1 

 to 3 fragile awns ; those of the disk-flowers with 2 unequal awns and 

 narrow wings; squamellae well developed. — Proc. Am. Acad. xv. 36 

 (1879). — Central Mexico. Specimens examined, — San Luis Potosi : 

 between the city and Tampico, Palmer, no. 1106, coll. of 1878-79 (type 

 in herb. Gray). 



30. Z. brevifolia, Gray. Fruticose or suffruticose, much-branched, 

 about 1 m. high : leaves ovate or oval, less than 2 cm. long, 1 cm. or less in 

 width, entire, obtuse at the apex, attenuate to subcordate at the base, 

 above strigose, beneath papillose-scabrous, the uppermost alternate : pedun- 

 cles long, slender, terminal, solitary, densely strigose ; heads 10 to 15 mm. 

 high; involucre lax, about 3-seriate, 1 cm. broad; the outer bracts ovate, 

 foliaceous at the apex : ray-flowers 5 to 8 ; ligules small ; disk-corollas 



