12Q PLANTJE WRIGHTIAN^. V. 



lanceolatis ; acheniis glanduloso-puberis ; pappo albo, setis pluriserialibus coiifoi-mi- 



]t,us. Prairies beyond the Pecos ; Aug. Valley near Messillas, Northern Mexico, 



Gregg ; who states that the plant grows from six inches to a foot high. — Mr. 

 Wrio'ht's specimens are from two to five inches in height. Leaves one to two 

 inches in diameter. Head nine to twelve lines in length ; the flowers light purple. 

 Pappus of copious and rather soft uniform bristles, not in the least clavellate or 

 thickened at the apex. Achenia (immature) apparently as in the preceding and 

 following species.* 



* Perezia, Lagasca, should without much doubt have the extension given to it by Lessing ; that is, it 

 should comprise Clarionea and Homoianthus, DC. But even Perezia of De Candolle must include Acour- 

 tia, Don, DC. ! (Perezia, Llave Sj- Lex.), Dumerilia, Less., DC, and Proustia, sect. Thelecarpoea, DC. (P. 

 reticulata, Don). The achenia are similar in all, linear or somewhat fusiform, attenuate above, or with a 

 more or less narrowed neck, and dilated at the apex into an epigynous disk which bears the pappus. There 

 is no available distinction between what is called the biserial pappus of Perezia, DC, &c., and the unise- 

 rial pappus of Acourtia. When the bristles are very copious, as in P. runcinata. Lag. (Clarionea, DC, 

 but a genuine CandoUean Perezia) and P. nana, they of course occupy more than one series ; but this is 

 equally the case in Don's Acourtia formosa, and in A. rigida, DC. ; while in A. hebeclada and my Perezia 

 Wrightii, the bristles being finer and perhaps fewer, they apparently occupy only one series. In A. for- 

 mosa and in several others, the bristles of the pappus are pretty rigid and more or less clavellate or thick- 

 ened (but not penicillate) at the apex ; but this character, which is of no more importance here than in 

 the genus Aster, is scarcely evident in some closely allied species, and disappears entirely in P. Wrightii, 

 P. nana, &c. There are a considerable number of Mexican species congeneric with De Candolle's species 

 of Acourtia, but I do not possess sufficient materials for their complete elucidation. 1 should remark, 

 however, that 



Perezia txjebinata, Llave ^ Lex. Nov. Veg. Descr. 1. p. 25, is doubtless the original Acourtia formosa, 

 Don, but not of De Candolle. Seemann gathered the plant in question in the northwestern part of Mex- 

 ico. The capitula are at least 25-30-flowered, and an inch in length, as P. turbinata is described : the 

 multiserial involucre may be justly likened to that of Serratula coronata, with which Don compares 

 the head of his Acourtia formosa ; and its form is strikingly turbinate, from the shorter exterior scales 

 passing into the numerous similar bracts which are imbricated on the upper part of the short peduncle. 

 The involucral scales are all lanceolate, attenuate-acuminate, of a dry and chartaceous texture, exactly as 

 in Perezia, DC, of which it is surely a true species. The copious and rigid bristles of the pappus cer- 

 tainly occupy more than one series ; the longer ones are a little thickened or more strongly denticulate 

 near the apex, but by no means " penicillate." The foliage apparently exhales the fragrance of lemon 

 in drying, as is the case with some other species. 



P. WisLizENi, Gray, PI. Fendl. p. Ill, is an allied species, with a very many-flowered hemispherical 

 involucre ; the exterior scales broadly ovate and lax ; the head more like that of P. (Clarionea, DC.) car- 

 thamoides than any other. The bristles of the rather copious pappus are rigid, and a little clavellate- 

 thickened at the apex. 



P. FRTJTicosA, Llave 4" Lex. I. c, accords very well as to the description with Acourtia formosa, DC ! 

 Prodr. 7. p. 66 (non Don), which I have seen from various parts of Mexico. It is in the Hookerian her- 

 barium from Mackenzie, and also a specimen from a plant raised in Kew Garden. The corymbose heads 

 are only about half an inch long ; the scales of the somewhat campanulate involucre ovate and ovate-lan- 

 ceolate, mucronate-acute, imbricated in about four series. The heads are not more than 15-fiowered. 

 The bristles of the rather rigid pappus are obscurely clavellate-thickened at the apex. Plainly this is not 

 Don's Acourtia formosa ; the heads of which are said to be as large as those of Serratula coronata ! and 

 the achenia to be half an inch long. — Dumerilia Alamani, DC. .' I. c. p. 67, belongs, I believe, to the same 

 species as his Acourtia formosa. It appears to be a state with the corymb imperfectly developed, the 

 heads sessile and fascicled on a very short peduncle among the upper leaves. The capitulum which I ex- 

 amined was 11-flowered ! 



