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PLANTS FENDLERIAN^E. 



lizenus found it very common along the Rio Grande nearly as far south as El Paso. Be- 

 fore this, the genus was known only from scanty specimens in Dr. James's collection, 

 made in Long's expedition, doubtless from the Upper Canadian, but the locality was not 

 recorded. In establishing the genus, Mr. Nuttall omitted to state that his plant was 

 derived from the collection of Dr. James, through Dr. Torrey, whose remaining specimen 

 being mislaid at the time and forgotten, the character of the genus in the Flora of North 

 America was drawn up from Nuttall's published description alone.* This requires emen- 

 dation as to the involucre, which is by no means gamophyllous. A second species with 

 some remarkable peculiarities having now been detected, the full characters of the genus, 

 and of the two species, are here subjoined. t The aspect is rather that of Zinnia than of 



* Dr. Torrey's remark in respect to the discovery of the plant, in Emory's Report, p. 144, is founded on 

 the same misapprehension as to the discoverer. 



t RIDDELLIA, Null. (char, augm.) 



^ Capitulum pluriflorum, heterogamum ; fl. radii 3, ligulatis, foemineis, persistentibus ; disci 6-9 tubulosis, 

 hermaphroditis. Involucrum cylindricum, pilis longis intertextis lanatum, e squamis 8-10 oblongo-linearibus 

 coriaceis rigidis conniventibus (sed discretis) uniserialibus, cum 3-6 interioribus anguste linearibus scariosis 

 a?quilongis, constans. Receptaculum planum, subalveolatum. Ligula? ratione capituli maxima?, e basi brevi- 

 ter tubulosa? abrupte dilatata? (latiores quam longse), plana?, apice 3-4-loba?, post anthesin ampliata? et char- 

 tacea?, persistentes. Corolla? disci tubulosa?, 5-dentati, dentibus glandulosis. Styli fl. hermaph. rami apice 

 capitellato-truncati minutim barbati. Achenia lineari-oblonga, 4 - 5-angulata, multistriata; radii Ieviter ob- 

 compressa. Pappus simplex, achenio brevior, 4 - 6-paleaceus ; squamellis oblongis vel lanceolatis, hyalino- 

 membranaceis, enerviis, muticis, subaequalibus, aut integris nudis, aut lacerato-piligeris ! — Herbs humiles, 

 floccoso-lanata?, ut videtur annua?, subaromatica?, caulibus fastigiato-ramosis foliosis ; foliis alternis oblanceola- 

 tis integerrimis, infimis et radicalibus spathulatis sa?pe paucidentatis vel subpinnatifidis ; glandulis immersis vix 

 ullia ; capitulis ad apicem ramorum corymbosis ; floribus aureis, ligulis post anthesin pallidioribus (sulphureis). 

 ' 1. R. tagetina (Null. I. c.) : ramis fastigiato-corymbosis ; foliis patentibus ; pedunculis capitulis longiori- 

 bus ; acheniis glabris ; pappi paleis obtusis integerrimis. — Plant 7 to 15 inches high, less woolly with age; 

 the erect-spreading branches usually fastigiate. Peduncles elongating after anthesis, becoming from half an 

 inch to an inch long. Rays from a quarter to over a third of an inch in length and breadth. Pappus almost 

 half the length of the disk-corolla. 



' 2. R. arachnoidea (sp. nov.) : caule parce ramoso foliisque dense lanatis strictiusculis ; corymbo conferto ; 

 pedunculis involucro brevioribus ; acheniis pilis longissimis arachnoideo-villosis ; pappi paleis diaphanis superne 

 in pilos arachnoideos pra?longos lacerato-diliquescentibus. — Dry soil, around Buena Vista and Saltillo, Dr. 

 Gregg, Br. Wislizenus : also near Monterey, Dr. Edwards. — Plant 6 or 8 inches high, with much the as- 

 pect of the preceding ; but the leaves are mostly narrower and the heads smaller and more crowded. The 

 rays, which are usually 4-lobed, in the dried specimens are orange-colored even when old (instead of sulphur- 

 yellow) as well as during anthesis. The delicate, cobwebby hairs which cover the young achenium are 

 much like those which densely clothe the involucre : they exceed the achenium itself in length, mingling with 

 those into which the thin, lanceolate pappus-scales are lacerate-dissected. In all other particulars this re- 

 markable species well accords with the former. 



