1420 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM 



Pubescent shrub; leaves opposite, the blades broad-ovate, 2.5 to 3.7 em. long 

 and about as wide, acute, coarsely acuminate-serrate, venose, scabrous above, 

 resinous-punctate and pubescent on the veins beneath, very short-petioled; 

 heads 4 to 6 at apex of branches, short-pediceled; involucre cylindric-subhemi- 

 spheric, the phyllaries imbricate, membranaceous, the outer small, the inner 

 oblong-linear, very obtuse, glabrous; receptacle paleaceous; flowers white; achenes 

 subtetragonous, villous, 4 mm. long; pappus of about 15 membranaceous fimbriate 

 obtuse squamellae about 1 mm. long. (Description compiled.) 



9. AGERATUM L. Sp. PI. 839. 1753. 

 Reference: Robinson, Revision of the genus Ageratum, Proc. Amer. Acad. 49: 

 454-483. 1913. 



Herbs or shrubs; leaves usually opposite, ovate or lanceolate; heads usually in 

 a terminal corymbose cluster on a long peduncle; involucre usually campanulate, 

 2 or 3-seriate, subequal, with narrow, somewhat indurate phyllaries; receptacle 

 naked or paleaceous; achenes 5-angled; pappus a paleaceous crown (in all the 

 following species) or of distinct or basally united, sometimes aristate squamellae. 

 Receptacle paleaceous. 



Leaves densely gray-pilose or tomentose beneath. 



Leaves lanceolate to ovate, acuminate to acute or obtusish, densely dotted 



with reddish glands beneath _* 1. A. paleaceum. 



Leaves ovate, obtuse or acute, not obviously gland-dotted beneath. 



2. A. albidum. 

 Leaves green and sparsely puberulous beneath. 



Leaves elongate-lanceolate, attenuate, sharply serrate. 



8a. A. salicifolium annectens. 



Leaves ovate, acutish, crenate 3. A. elassocarpum. 



Receptacle naked. 



Leaves ovate to ovate-oblong, about twice as long as wide, if rarely lanceolate 

 then narrowed to an obtuse tip. 

 Leaves dull green or only slightly shining above, beneath dull and usually 

 rather densely pubescent. 



Leaves densely whitish-tomentose beneath 4. A. tomentosum. 



Leaves from nearly glabrous to grayish-tomentose beneath. 



5. A. corymbosum. 

 Leaves bright green and shiny above, beneath paler but green, and sparsely 

 puberulous on the nerves. 

 Leaves crenate-serrate; corollas bluish; stem subglabrous. 



6. A. scabriusculum. 

 Leaves serrate; corollas white; stem densely incurved-puberulous. 



7. A. lucidum. 

 Leaves narrowly lanceolate, attenuate, 3 to 5 times as long as wide. 



8. A. salicifoliura. 

 1. Ageratum paleaceum (C. Gay) Hemsl. Biol. Centr. Amer. Bot. 2: 83. 1881. 

 Coelestiiia palcacea C. Gay; DC. Prodr. 5: 107. 1836. 

 Carelia paleacea Kuntze, Rev. Gen. PI. 1: 325. 1891. 

 Ageratum rhytidophyllum Robinson, Proc. Amer. Acad. 36: 476. 1901. 

 Oaxaca; tj^pe collected near City of Oaxaca. 



Frutescent, about 60 cm. high; leaves short-petioled, the blades lanceolate to 

 ovate, acuminate to acute, beneath reticulate, canescent-pilose, and densely 

 dotted with reddish glands, 2.5 to 4 cm. long, 8 to 22 mm. wide; corollas purplish 

 Ijlue toward apex. 



