200 PKOCEEDINGS OF THE AMERICAN ACADEMY 



turn, dorso bigibberoso-saccatum. Perigoniuin 6- (raro 5-)partitum, 

 segmentis oblongo-lanceolatis requalibus. Stamina segmentis perigonii 

 numero requalia, basi eorum inserta, quandoque pauciora. Acbeuium 

 triquetrum. Embryo in albumine carnoso vel farinoso copioso excen- 

 tricus, cotyledonibus orbiculatis radicular accumbentibus. — Herbas an- 

 nua^ Californicae, caulibus tenuibus dicbotomo-ramosissimis diffusis, foliis 

 oppositis, inferioribus s*pe bilobis lobis nunc iterum 2-3-lobatis, superi- 

 oribus quandoque pi. m. crenulato-denticulatis; involucris primum mini- 

 mis terminalibus alaribusque subsessilibus ; floribus flavidulis parvis. 



The involucre has been, as we suppose, wrongly described as di- 

 phyllous. It is rightly said by Hooker (in Bot. Beechey) to be " two- 

 lobed." These lobes may answer each to one of a pair of leaves, like 

 the cauline, but united on one side, in a manner sometimes observed in 

 the bracts of Oxytlteca ; but we are confident that the whole rather 

 answers to a single bracteolar leaf, which is two-lobed after the fashion 

 of the lower cauline leaves ; and so is homologous (not with the invo- 

 lucre of Eriogonum but) with a bractlet in Nemacaulis* Bentham's 

 view (in Bot. Sulph. & DC. Prodr. 14, p. 27), first, that there are a 

 pair of these involucral leaves, and second, that each is composed of 

 three leaves, the contiguous margins of which expand into the dorsal 

 wings or crests, is most of all untenable. These crests are gibberosities, 

 one for each lobe, sometimes shallow or inconspicuous, sometimes very 

 deep and large, and crest-like or wing-like. 



1. P. drymarioides, Fischer & Meyer, Ind. Sem. Petrop. 2, p. 23, 

 & Sert. Petrop. fasc. 3, tab. fol. ; Hook. & Arn. Bot. Beech, t. 90. 

 Tenella, pilosulo-pubescens ; foliis inferioribus longe petiolatis flabelli- 

 formibus obcordato-bilobis seu emarginatis nunc bis bilobis, superioribus 

 ramealibusque rotundatis obovatis spathulatisque haud raro crenulato- 

 denticulatis ; involucro fructifero (lin. l~13rlongo) profundius bilobo 

 margine dentato vel laciniato. P. microphylla, diphylla, & var. biloba, 

 Nutt. PI. Gamb. 1. c. — Common in California along the coast : very 

 variable. 



2. P. macroptera, Benth. Sulph. p. 44. Major, rigidior ; ramis 

 junioribus cano-pubescentibus ; foliis (ramealibus) spathulatis integer- 

 rimis subcarnosis vix petiolatis ; involucro fructifero (semipollicari) 

 margine sinuato. — Bay of Magdalena, Lower California, Hinds. 



* Payer, who in his Organogenie, tab. 64, has well shown its development, we 

 find, takes a similar view. 



