Pentachceta. COMPOSITE. 3Q5 



who veiy probably found it only in Arizona, where it has since been collected by Dr. Antisdl and 

 Dr. Palmer, and in S. Utah by Parry. Heads less than half an inch in diameter. Leaves 

 linear-lanceolate and somewhat spatulate, half an inch or less in length, about a line wide. 

 Akenes 2 lines long, when mature resembling pellets of wool. 



10. PENTACHCETA, Nutt. 



Heads solitary, terminating slender branches, heterogamous with the rays fertile, 

 or sometimes rayless, several - many-flowered. Involucre of numerous or rather few 

 thin and smooth more or less scariously margined oblong or lanceolate scales, loosely 

 imbricated in two or more series, destitute of green tips. Receptacle convex, some- 

 what foveolate. Eays few or numerous, with oblong ligule on a slender tube, or 

 sometimes the ligule and sometimes the whole pistillate ray-flowers wanting. Disk- 

 corollas 5-toothed. Anthers tipped with a small subulate appendage. Branches of 

 the style in the disk-flowers bearing a long filiform-subulate but flattish appendage, 

 much longer than the stigmatic portion. Akenes oblong, compressed, hirsute. 

 Pappus of 5 (rarely somewhat fewer or more numerous) slender and rigid persistent 

 serrulate-scabrous bristles, which are shorter than the disk-corollas, abruptly en- 

 larged (but not paleaceous) at the very base, occasionally unequal, sometimes all 

 reduced to short rudiments or wholly obsolete. Low and slender annuals (wholly 

 Californian), more or less pubescent, or sometimes glabrous, with filiform-linear and 

 entire alternate leaves, and small or middle-sized heads. Corollas either all yellow, 

 or those of the disk sometimes turning purple, the rays when present usually yel- 

 low, sometimes white ! Torr. & Gray, Fl. ii. 249 ; Gray, Proc. Am. Acad. viii. 

 633. Aphantochceta, Gray in Pacif. R Eep. iv. 43, t. 11. 



A peculiarly Californian genus of two species (P. gracilis, Benth., of Mexico, being an Oxy- 

 pappus), remarkable for having, like Lessingia, either yellow or white rays. 



1. P. aurea, Nutt. At length diffusely branched, 3 to 12 inches high: heads 

 many-flowered : scales of the involucre lanceolate, mostly acuminate or acute, and 

 with broad and thin scarious margins, the outer successively shorter : rays 7 to 40, 

 deep golden yellow : pappus of 5 (or sometimes 6 to 8) bristles. 



Dry plains, southern part of the State, chiefly known from San Diego Co., Nuttall, Parry, &c. 

 Leaves an inch or less in length, the upper reduced to small subulate bracts on the terminal 

 peduncle. Heads varying from a quarter to half an inch in length. Mature akenes not seen, 

 but apparently compressed as in the next. To this apparently belongs both the varieties described 

 in Bot. Mex. Boundary, 81. 



2. P. exilis, Gray, 1. c. Erect or with ascending branches, 3 to 8 inches high : 

 scales of the involucre oblong, obtuse, but commonly mucronate, all of nearly equal 

 length and with narrow scarious margins : heads in the larger forms many-flowered 

 and with 10 to 14 sulphur-colored or sometimes white rays : pappus of 5 equal or 

 somewhat unequal bristles, or occasionally with some or all the bristles obsolete. 

 (To this belongs the P. aurea of Bigelow's collection in Whipple's Expedition, of 

 Bolander'a Catalogue, &c.) 



Var. discoidea. Heads with from 9 to 20 disk-flowers and no rays : bristles 

 of the pappus present. 



Var. aphantochaeta. Heads, &c., as in var. discoidea, or with 3 to 5 pistillate 

 marginal flowers destitute of ligule : pappus obsolete or nearly so. Apkantochceta 

 exilis, Gray, 1. c. 99, t. 11. 



Hillsides, from Santa Cruz to NapaCo., &c. Much like the foregoing, except in the particu- 

 lars mentioned. Scales of the involucre seldom over 2 lines long, about 16 or 18 in the fuller- 

 flowered heads, occupying two ranks of about equal length, reduced to 7 or 10 and sometimes 

 almost to a single rank in the fewer-flowered and depauperate states. Mature akeiies flat and 



