ROBINSON. — DIAGNOSES OF AMERICAN EUPATORIEAE. 271 



II. DIAGNOSES AND NOTES RELATING TO AMERICAN 

 EUPATORIEAE. 



By B. L. Rob ins ox. 



Ophryosporus venosissimus, u. comb. Eupatorium venosissimum 

 Rusby, Mem. Torr. Bot. Club, vi. 57 (1896). The authers of this 

 species, even when examined with a compound microscope, show no ves- 

 tige of an apical appendage. In other respects, such as the few subequal 

 scales of the involucre, the species is in agreement with Ophryosporus. 

 In habit and foliage it somewhat resembles 0. Cumingii, Benth. 



The genus Ageratella seems never to have received a formal or 

 detailed characterization. It was originally founded (without generic 

 description) upon two plants which Dr. Gray regarded as varieties of a 

 single species. Hoffmann, in Engl. & Prantl, Nat. Pflauzenf. iv. Abt. 5, 

 p. 137 (1890), also regarded the genus as monotypic and gave only a 

 comparative, 2-line description of it. With the more abundant material 

 now at hand it is clear that there are two distinct species. The generic 

 characters and specific distinctions may be recorded as follows : — 



Ageratella, Gray. Capitula homogama, cylindrica vel anguste cam- 

 panulata, ca. lo-flora. Involucri squamae valde inaequales, in seriebus 

 5 verticalibus imbricatae, exterioribus brevibus ovatis, iuterioribus lon- 

 gioribus lanceolato-oblongis, intimis linearibus angustissimis deciduis pa- 

 leiformibus. Receptaculum hemisphaericum, nudum, parvum. Corollae 

 anguste tubulosae sine ullis faucibus distinctis summa parte plus minusve 

 contractae, externe sparse glandulosae, dentibus limbi 5 anguste oblongis 

 brevissimis erectis. Antherae oblongae, basi obtusae, connectivo apice 

 incrassato truucato vel in appendicem brevem obtusam producto. Achae- 

 nia 5-gona, prismatica, deorsum leviter angustata, in costis sursum his- 

 pidula. Pappi paleae ovatae vel lanceolatae, translucidae, erosae, costa 

 unica hispidula in aristam longam purpurascentem producta. Styli rami 

 elongati, leviter clavellati. — Gray ex Wats. Proc. Am. Acad. xxii. 419, 

 420 (1887) ; Hoffm. in Engl. & Prantl, Nat. Pfianzenf. iv. Abt. 5, 

 p. 137 (1890). — Frutices vel suffrutices graciles, humiles, ramosi. 

 Folia parva, opposita vel alterna, ovata vel oblonga vel linearia. Capit- 

 ula numerosa, mediocra, racemosa vel paniculata. 



A. microphylla, Gray, 1. c. Fruticosa copiose paniculatini ramosa ; 

 ramis gracillimis subteretibus decumbentibus puberulis apice nudiusculis 



