VI. PLANTS WRIGHTIAN^, 105 



and aspect of this plant are almost exactly as in M. sonchoides, with which I for- 

 merly confounded it. That species, however, as stated by Dr. Torrey (Appendix to 

 Siansbiirfs Report, p. 392), has five stronger and persistent bristles to the pappus. 

 The achenium, moreover, is strongly angled with five thick and equidistant ribs, 

 which are much larger than the others (two in each interval), and alternating with 

 the stronger setae of the pappus ; and its apes is very minutely denticulate, but not 

 produced into a cup or distinct border. In M. Fendleri, the ribs of the brownish 

 achenium are slender and all alike, and its apex is continued into a decided cup, 

 with an even edge, Avithin which the row of minute denticuli, like persistent bases 

 of the setae of the pappus, are concealed ; and only one (sometimes two ]) of the 

 rays of the pappus is stronger and persistent. — The Californian plant of Coulter's 

 collection, which I also inadvertently referred to M. sonchoides, is doubtless M. 

 obtusa, Benth. ; likewise gathered by Dr. Parry, at Monterey. In this the achenia, in 

 Parry's specimens, are tapering to the base, somewhat angled, but evenly multistri- 

 ate, and with scarcely any apical border; the pappus is wholly deciduous in a ring; 

 and I find no stronger and naked bristles. — Dr. Torrey indicated to me an analo- 

 gous structure in the pappus of Sonchus, in which four or five of the inner bristles 

 of the pappus are much stronger than the soft and delicate exterior pappus. This, 

 I find, has been duly noticed by C. H. Schultz, in the PJij/top-ajihia Canariensis 

 of Mr. Webb. 



PRE^"A^•THES 1 EXiGUA (sp. uov.) : caule 3 - 4-pollicari raniosissimo ; pedunculis 

 divaricatis ; foliis radicalibus caulinisque oblongis vel obovatis basi attenuatis spi- 

 nuloso-dentatis nunc sinuatis, ramealibus ad bracteas minimas reductis ; involucre 

 tetraphyllo quadrifloro ; acheniis 5-sulcatis scabriusculis pappo rigido sublongiori- 

 bus. — Stony hills above El Paso ; Aprik (1425.) — Eoot simple, annual or bien- 

 nial. Leaves 6 to 10 lines long, glabrous. Stem soon deliquescent into a diffuse 

 and corymbose compound panicle. Involucre 2 lines long, subtended by a minute 

 bract, like those of the peduncles and branchlets ; the scales oblong-lanceolate. 

 Ligules short; the color not known, probably flesh-colored. Achenia cylindrical, 

 scarcely narrowed at the base, truncate at the apex, the surfice occupied by five 

 very broad and flat ribs, separated by narrow grooves, minutely scabrous. Pappus 

 bright white, of copious and very unequal bristles, which are unusually stifi" and 

 rigid, slightly thickened downwards, minutely scabrous, the smallest less than half 

 the length of the longest, and these rather shorter than the achenium, at length 

 separating in a ring. This plant seems to fall more readily into Prenauthcs than 

 into any other genus known to me; but it may not be a true congener of the 

 European species. 



Lygodesmia aphylla, var. Texana, Torr. Sf Gray, Fl. 2. pi. 485. Stony hills of 

 the Pecos ; June. (1302.) 



Mi-LGEDiuM Pt-LCHELLUM, Nutt. / Torr. Sf Gray, Fl. 2. p. 498 ; Gray, PL Feudl. 

 p. 115. Banks of the Limpio and of the Rio Grande; also at the copper mines, 

 New Mexico. (1303.) 



Ptrrhopappus Carolixianus, DC. Prodr. 7.^x44; Torr. Sf Gray, Fl. '2. p. 495. 

 Along the Rio Grande, above El Paso ; May. (1426.) 



