I » 



VOLUME LXX 



NUMBER 2 







i 



i 



THE 



Botanical Gazette 



AUGUST 1920 



studies in the genus bidens. V 



CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY 269 



Earl E. Sherff 



(with plates xi-xiv) 



Bidens exigua, sp. nov. (pi. XI). — Herba annua, 1.5-3 dm. alta; 

 caule tenuissimo, subrecto, striato, subsimplici. Folia opposita 

 (summa alternata), membranacea, petiolata, petiolo adjecto 3-5 cm. 

 longa, bipinnata, glabra; foliolis (3 aut 5) maximam partem 

 3-5-partitis; lobis integris, subobtusis, infirme apiculatis. Petioli 

 o . 5-2 cm. longi, basi connati. Capitula pauca aut solitaria, dis- 

 coidea, tenuiter pedunculata pedunculis 2-5 cm. longis, ad anthesin 

 5-6 mm. longa et 1. 5-2 mm. lata infra, 2-3 mm. lata supra; in 

 fructu, circ. 9 mm. longa et 2-5 mm. lata. Involucrum basi 

 sparsim hispidum aut glabratum; bracteis duplici serie dispositis; 

 exterioribus (4-7) linearibus, 2-$ mm. longis, ciliatis, ad faciem 

 glabris aut pubescentibus, ad apicem induratis; interioribus dimidio 

 longioribus, glabra tis, lanceolatis, stria tis, margine dia[>hanis. 

 Achaenia (submatura) linearia, glabra aut supra ad margines 

 remote hispida, bi- aut triaristata aristis retrorsum hamosis ham is 



tenuibus, 4-8 mm. longa. , 



Specimens examined. 



H. T. Townsend 15 13, alt. 1607 m., Chosica 



Canyon, Peru, April 20, 1913 (Herb. U.S. Nat. Mus., no. 602943, type). 



The plants of the type sheet would seem at first to be merely depauperate 

 or impoverished forms of some species normally larger and perhaps already 

 described. The technical characters, however, do not match those of any other 

 species known to me. There are several species very close to B. exigua all of 



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