636 PROCEEDINGS OF THE AMERICAN ACADEMY. 



ceeded by the leaves, and in the lack of leaf-like bracts subtending the 

 larger branches of the inflorescence. From one another they differ 

 moist markedly in the size and dentation of the leaves, but also in the 

 character of the pubescence on the upper leaf-surface. In P. Stramo- 

 nium it is velvety, in P. Arctium arachnoid-tomentose. In P. Stra- 

 monium the panicle is nodding, in P. Arctium it is upright. Both 

 species occupy the same floral region and are the northwestern congen- 

 ers of the southeastern P. tomentosum and its allies. 



Parthenium Lozanianum, n. sp., fruticosum ramosum usque ad 

 2.5 m. altum, ramis ochraceis subsulcatis juventate exigue albo-tomen- 

 tosis, aetate glabris ; internodiis quam foliis saepe duplo brevioribus. 

 Folia plerumque lyrato-partita 2-4.5 cm. lata 4-9 cm. longa, supra viri- 

 dia exigue crispo-pubescentia, subtus molliter albido-tomentosa, parte 

 terminali circumscriptione triangula vel cuneato-lanceolata ipsa fere 

 generis Aceris modo obtuse dentata lobataque, partibus inferioribus 

 parvis vel nullis basi in petiolum 3-6 mm. longum decurrentibus. In- 

 rlorescentia terminalis ex corymbis 5-6 sublaxis constans. Bracteae 

 deorsum foliis superioribus similes sursum gradatim minores et lan- 

 ceolatae vel lineares. Inflorescentiae ramuli pedicellique puberulo- 

 tomentosi graciles. Capitula diametro et altitudine ca. 5 mm. Involucri 

 squamae 10 biseriatae exteriores late ovatae acutiusculae interiores 

 suborbiculares basi truncatae apice obtusissimae. Radii flores 5, tubo 

 brevi, limbo suborbiculari apice emarginato aut raro tridentato. 

 Achenia nigra hirtella compressa cuneata 2.5 mm. longa ad margines 

 singula palearum aristis florum duorum sterilium adnata. Pappi aris- 

 tae 2 nigrae arcuato-ascendentes tubum superantes albo-pubesdentes. 

 Disci flores ca. 26 in axillis palearum cuneatarum pubescentium positi. 

 — Nuevo Leon, State of Nuevo Leon, alt. 300 m., Lozano, no. 10,247 

 (type, in hb. Gray). A member of De Candolle's section Partheni- 

 chaeta and very closely allied to P. incanum HBK., from which it 

 may be distinguished by its incurved, ascending pappus-awns and green 

 ujiper leaf surface. In P. incanum the pappus-awns are divergent or 

 often recurved, and the leaves are whitened above. 



Perez] \ adnata Gray. This species has long been considered iden- 

 tical with Perezia Alamani Hemsl. Specimens which have accumu- 

 lated in recent years afford evidence that not only may Perezia adnata 

 and P. Alamani be distinguished, but also a third plant which is here 

 described as a variety of the former. The following brief descriptions 

 contrast the diagnostic characters of the three plants. 



Perezia Alamani (DC) Hemsl. involucri bracteis ca. 14 paene 

 glabris submembranaceis anguste lanceolatis viridibus apice purpureo- 

 tinctis basi vix callosis ; pappi setulis ca. 49 ; labro corollae interiore 



