Hofmeisteria. COMPOSIT.^. 93 



Margacola pnrvula, Buckl. in Proc. Acad. Philad. 1861, 18G2. — "Wet ground iu prairies, 

 Texas, Wright, Buckley, &c. (Mex., Pu/mn:) 

 T. rivularis. Gray, 1. c. Steans floating, in sli^llow water rooting, and flowering branches 

 emersed and ascending: leaves succulent, mostly opposite, an inch or two in length, cuneate- 

 obovate, sparingly incised or pahnately 3-lobed, contracted into a narrow counate-clasj»ing 

 auricniate base: heads fewer or solitary on simple peduncles, 3 or 4 lines in diameter: 

 involucral bracts about 12, oval, obtuse : recej^tacle highly convex : tube of corolla slender, 

 ecpialling the hemisijherical throat and limb : style-branches flat and linear, acutish : pappus 

 a minute and evanescent or obscure setulose crown. — In springs and streamlets, S. W. 

 Texas, Wright, &c. (Adjacent Mex., Gregg, &c.) 



7. AGERATUM, L. (Ancient Greek and Latin name of some aromatic 

 plant of this order, probably an Achillea, from a privative and y>/pas, yriparo'i^ 

 not waxing old, transferred by Linna3us to an American genus.) — Cliiefly 

 tropical, herbaceous, and with opposite petiolate leaves ; heads small in terminal 

 corymbiform cymes or rarely jjaniculate ; flowers blue, puri)le, or white, in 

 summer. — Benth. & Hook. Gen. ii. 241, excl. syn. Oxijlohus. Ageratum & 

 Cwlestliia, Cass., DC. ; to which should be added AJomia, IIBK., differing only 

 in the want of pappus. 



§ 1. EuAGERATUM. Papjius of dihtinct aristate or sometimes muticous paleae : 

 receptacle naked. 



A. coxYzofoEs, L. Annual, pubescent : leaves ovate or deltoid-subcordate, crenately serrate : 

 pappus of 5 to 7 lanceolate rigid scales, mostly tapering into a scabrous awn whicli nearly 

 equals the blue or white corolla. — Sclik. Handb. t. 238 ; Hook. Exot. Fl. t. 15. A. 3Icxicu.num, 

 Sims, Bot. Mag. t. 2524, &c., a more pubescent form, common in ornamental cultivation. — 

 Sparingly naturalized near towns in the S. Atlantic States. (Nat. from Trop. Amer., &c.) 



§ 2. CcELESTixA. Pappus corouiform or cupnlate (by the union of the paleas 

 into an entire or toothed cup or border), sometimes obsolete. — Coelestina, C'ass., 

 DC, &c. (In our species the receptacle is naked, duration of root uncertain, 

 and flowers usually blue or violet.) 



A. COrynibosum, Zuccagxi. Scabrous-pul)erulent, erect : leaves short-petioled, ovate 

 to ob]niig-]ance(jlate, irregularly few-several-toothed : floriferous branches naked above: 

 corolla-tube glanduliferous : pappus prominently cujjulate, more or less dentate. — Zuccagni 

 ex Ball), in Ilort. Taur. 1806; Ters. Syn. ii. 402. A. calestinum, Sims, Bot. Mag. t. 1730; 

 Lodd. Bot. Cab. t. 623. Ccelcstina ageratoides, IIBK. N(jv. Gen. & Spec. iv. 151 ; Gray, PI. 

 AVright. ii. 70. C ccerulea, Cass. Diet. vi. suppl. 8, t. 93. C. corymhosa, DC. Prodr. v. 108. 

 — Xcw Mexico, Wright, &.C. (Mex.) 



A. littorale, CiRay. Glabrous, decumbent or assurgent : leaves rather succulent, long-peti- 

 olcd, ovate with cuneate ba.se, serrate : corolla glabrous : pappus au extremely short crown, 

 with or without several minute narrow teeth, or reduced to a mere ring. — Proc. Am. Acad, 

 xvi. 78. — Calf'stina maritiina, Torr. & Gray, Fl. ii. 64; not Ageratum rnaritiinum, IIUK., 

 which is a true Ageratum with diminutive pappus. — Key West, S. Florida, Bennett, Blod- 

 gc.tt, Palmer, Garber. 



8. HOFMEISTERIA, Walp. (W. Hofmeister, a vegetable histologist.) 

 — Low suffrutescent plants ; with heads terminating slender peduncles, small 

 incised leaves either opposite or alternate on long petioles, and whitish flowers ; 

 the style-branches clavate. — Two species, tlie original one (// fascicuJata, 

 Walp. Rep. vi. 106 ; IMogyne, Benth. Bot. Sulph. 20, t. 14), of Lower California, 

 with 2-3-awned pappus. 



H, pluriseta, Gray. Slightly pubcrulentand viscidulous, much branched : leaves with small 

 (2 to 5 lines long) deltoid to oblong blade very much shorter than the petiole: heads about 



