GREENMAN, — GENUS LIABUM. 293 



Nov. Gen. & Spec. iii. 38G ; Bot. Mag. 4223. u^ginetia longijiora^ Cav. 

 Ic. vi. 51, t. 257, f. 1. 



H. (Macrououstonia) triflora. Gray, 1. c, Hemsl. 1. c, is a good 

 Bouvardia. 



From the technical characters of complete specimens of the last two 

 species, now at hand, there seems no reason for retaining them in the 

 genus Houstonia. 



11. KEY TO THE MEXICAN SPECIES OF LIABUM. 



* Leaves ovate or ovate-deltoid : heads radiate. 



t- Leaves ovate-deltoid, more or less deeply sinuate-dentate and mucronate-denticu- 



late : heads few, large (3 to 5 cm. in diameter), terminating the stem. 



L. Andrieuxii, Benth. & Hook. f. Gen. ii. 437. Vernonia Andrieuxii, 

 DC. Prodr. V. 16. 



•»- -t- Leaves ovate, entire or mucronate-denticulate : heads disposed in terminal 



panicles. 

 ++ Pappus of slender unequal setae, not biseriate. 

 = Involucral scales lance-attenuate : petioles winged and often dilated about the 

 stem : ligules narrow : achenes pubescent. 



L. asclepiadeum, Schz. Bip. Linnaea, xx. 521. 



= = Involucral scales oblong, obtuse : ligules ovate : achenes glabrous. 

 L. polyanthum, Ivlatt, Bull. Soc. Bot. Belg. xxxi. (1892), 209. 

 ++ *+ Pappus distinctly biseriate, outer series short, paleaceous. 

 = Achenes pubescent. 

 L. andromachioides, Benth. & Hook, f. Gen. ii. 43G. Vernonia 

 andromachioides^ Less. Linntea, vi. 397, 645. 



L. Deppeanura, Hemsl. Biol. Centr.-Am. Bot. ii. 232. Andro- 

 machia Deppeana, Less. Linncea, vi. 401. 



= = Achenes glabrous. 

 L. platylepis, Schz. Bip. Flora, 1856, 160; Klatt, Leopoklina, 

 xxiii. (reprint, p. 7). 



L. discolor, Benth. & Hook. f. Gen. ii. 436. Sinclairia discolor, 

 Hook. & Arn. Bot. Beech. 433 ; Hook. Ic. PL v. t. 451. 



* * Leaves ovate or ovate-lanceolate : heads discoid. 



1- Inflorescence in loose terminal pyramidal panicles : involucre 3-5-seriate : 



pappus biseriate. 



t-f Immature achenes stipitate-glandular : involucral scales obtuse. 

 Li. glabrum, Hemsl. 1. c. 



