90 BOTANICAL GAZETTE [august 



which might once easily have passed for B. bipinnata L., yet which, with 

 subsequent advances in our knowledge, have been proved indisputably to be 

 distinct and severally valid. Among these are B. hekrospcrma Gray and 

 B. Lemmoni Gray of the southwestern United States and Mexico, and B. parvi- 

 flora Willd. of Asia. B. exigua is nearest to B. Lemmoni and B. parviflora; 

 like these, it may well be expected to prove constant and worthy of specific 

 rank. 



Bidens duranginensis,sp. nov. (pi. XI). — Herba annua, glab rata, 

 demum circa 6-9 dm. alta; caule subtetragono, ramis acute 

 tetragonis, ramis acute tetragonis, longis et tenuibus, striatis, 

 infra minute pubescentibus. Folia opposita, petiolata, petiolo 

 adjecto 10-12 cm. longa (eis ramorum 1-3 cm. longis), pinnata, 

 serrata aut dentata (aut etiam inciso-dentata) , ciliata, foliolis 

 ovatis aut ovato-lanceolatis, saepe duobus aut quatuor imis cuius- 

 que folii tripartitis. Petioli (foliorum caulis) 2 . 5-4 cm. longi, 

 ad basim ciliati et connati. Capitula multa, subligulata, tenuiter 

 pedunculata, pedunculis 3-8 cm. longis, ad anthesin 4-7 mm. alta et 

 (ligulis adjectis) 0.8-1.3 cm. lata, in fructu 1. 2-1. 4 cm. alta et 

 6-8 mm. lata. Involucrum basi hispidum, bracteis duplici serie 

 dispositis; exterioribus (circ. 8) linearibus, fere glabris, apice 

 induratis, 2-3 mm. longis; interioribus dimidio longioribus, anguste 

 lanceolatis; membranaceis, margine diaphanis. Ligulae (3-6) sub- 

 albidae, anguste ovatae, 4-7-striatae, 4-6 mm. longae. Achaenia 

 linearia, nigra, glabra aut supra sparsim hispida, 2-4-aristata 

 aristis navis et retrorsum hamosis, corpore 6-12 mm longa. 



Specimens examined. — Dr. Edward Palmer 756, west side of Iron Moun- 

 tain, vicinity of city of Durango, Durango, Mexico, October 1896 (Herb. 

 Gray, type; Herb. Field Mus., no. 51825; Herb. U.S. Nat. Mus.) ; idem 612, 

 vicinity of city of Durango, Durango, Mexico, April to November 1896 (Herb. 

 Field Mus., nos. 51704 and 51705; Herb. Gray, differing from type material, 

 apparently, merely in being somewhat younger). 



This species, if we attempt to delimit it in a taxonomic way, is confessedly 

 of unsatisfactory status. The type collection had been determined as Bidens 

 anthriscoides DC., but the plants are very different from the type material of 

 that species {Berlandier 1010, Herb. Brit. Mus.; Herb. Drake, Paris). It 

 is manifestly an ally of B. pilosa L., from which it differs in its whitish rays and 

 in its foliage, the lower leaflets of the stem leaves tending to be distinctly 

 tripartite. This last character distinguishes it likewise from B. hucantha (L.) 

 Willd. In foliage characters it slightly simulates B. chinensis (L.) Willd. of 



