126 



PLANT^ ■WRIGHTIANiE. 



V. 



lanceolatis ; acheniis glanduloso-puberis ; pappo albo, setis pluriserialibus conformi- 

 bus. — Prairies beyond tlie Pecos ; Aug. Valley near Messillas, Nortbern Mexico, 

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

 Wrigbfs specimens are frora two to five inches in height. Leaves one to two 

 inches in diaracter. Head nine to twelve lines in length ; tbe flowers light purple. 

 Pappus of copious and rather soffc uniform bristles, not in tlie 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 Homolanthus, DC, But even Perezia of De Candolle must include Acour- 

 tia, Don^ DC, ! (Perezia, Llave S^- Lex.)^ Dumerilia, 1.^55., DC, and Proustia, sect. Thelccarpcea, DC. (P. 

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



■ 



niore or less narrowed neck, and dilatcd 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 Candollean 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 fincr and perhaps fewer, they apparently occupy only one series. In A. for- 

 mosa and In several others, thc 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 CandoIle's species 

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

 however, that 



PiiREziA TURBiNATA, Llave ^ Lcx, Nov, Vcg, Descr, 1. p, 25, is doubtless the original Acourtia formosa, 

 Don^ but not of De CandoIIe. 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 

 multiscrial involucre may be justly hkened to that of Serratula coronata, with which Don compares 

 the head of his Acourlia 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 rigld bristles of the pappus cer- 

 tainly occupy more than one series; the longer ones are a little ihickened 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. WisLizENl, Gray, PL Fendl p. 111, is an allied species, with a very many-flowered hemispherical 

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

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

 thickened at the apex. 



P. FRUTicosA, Llave ^^ Lex. L c, accords vcry well as to the descrlptlon wlth 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 ralsed in Kew Garden. The corymbose heads 

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

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

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

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

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

 spccles as his Acourtia formosa. It appears to be a state with the corymb imperfcctly developed, tlie 

 heads sessile and fasciclcd on a \cr^' short pcduncle among the upper leaves. The capitulum which I cx- 

 amined wus 11-flowercd ! 



