177 
at base: heads about 6 mm. long: involucral bracts acuminate or slender-apiculate: 
achenes 2 mm. long, resinous-atomiferous.—An Atlantic species, extending through- 
out Texas in moist ground along streams. Var. PUBESCENS Torr. & Gray is from 
slightly to densely puberulent, extending from the Gulf States into Texas. 
2. M. cordifolia Willd. Puberulent or pubescent, frutescent at base: leaves 
broadly cordate: inflorescence more compound: heads 8 to 10 mm. long: involucral 
bracts obtuse or pointless: achenes 3 to 4 mm. long, glabrous.—A species extending 
from western Louisiana into Mexico, 
6. EUPATORIUM Tourn. (THOROUGHWORT.) 
Erect perennial herbs (sometimes shrubby), often sprinkled with bitter 
resinous dots, with commonly opposite leaves, generally corymbose 
discoid 3 to many-flowered heads, white, bluish or purple perfect flowers, 
cylindrical or bell-shaped involucre of more than 4 bracts, flat or con- 
ical naked receptacle, 5-toothed corolla, 5-angled achenes, and pappus 
a single row of slender capillary barely roughish bristles. 
§ 1. Involucre cylindrical, of scale-like coriaceous or firm striate bracts closely imbricated 
in many series: receptacle flat or rarely convex, 
1. EB. ivefolium L. Herbaceous or nearly so, somewhat hirsute or pubescent, 6 
to 15 dm. high: leaves lanceolate or the upper ones linear, hardly petioled, sparsely 
and often coarsely serrate at middle, mostly obtuse, 2.5 to 5 em, long: cymes small 
and loose: tips of involucral bracts purple or greenish and slightly squarrose-spread- 
ing: flowers light purplish-blue or reddish.—From Louisiana through Texas to 
Mexico. 
2, E. conyzoides Vahl. Shrubby, with herbaceous flowering branches, villous- 
pubescent to glabrate, 12 to 380 dm. high: leaves ovate-lanceolate to ovate, slender- 
petioled, sparsely and acutely serrate or sometimes entire, acuminate, mostly cuneate 
at base, 2.5 to 12.5 cm long: heads numerous in the open cymes: involucral bracts 
without appendage and appressed: flowers pale blue or white.—Along the Rio 
Grande. 
§ 2. Involucre various, the bracts from thin-membranaceous or scarious to herbaceous, nerve- 
less or few-nerved, mostly lax, either imbricated or equal and nearly in one series; recep- 
tacle flat, 
* Involucre cylindrical, the purplish bracts numerous and closely imbricated in several 
rows of unequal length, slightly striate. 
3. B. purpureum L. (JoE-PYE WEED. TRUMPET WEED). Stout and tall simple 
stems, 6 to 36 dm. high: leaves 3 to6 in a whorl, oblong-ovate or lanceolate, pointed, 
very veiny, roughish, toothed: corymbs of flesh-colored flowers very dense and 
compound.—Low or wet ground, Var, MACULATUM Darl, is 9 to 12 dm. high, often 
roughish-pubescent, with commonly purple stem and somewhat rugose leaves, and 
more compact and depressed inflorescence. 
** Involucre imbricated, rather lax, the bracts of at least 3 (seldom only 2) lengths, the 
outer successively shorter. 
+ Heads 20-flowered or more, large (about 12 mm. long): involucral bracts of 4 or 5 
lengths, striate-nervose. 
4. E. Parryi Gray. Hirsutely pubescent, loosely branched: leaves alternate, 
broadly ovate and rather deeply cordate, crenately dentate, acute or acuminate, 
slender-petioled: heads of white flowers rather few in an open panicle: involucral 
bracts thin, oblong-lanceolate, acuminate, the innermost produced into a setiform 
tip: achenes minutely pubescent.—On the Mexican side of the Rio Grande, and prob- 
ably also in Texas. 
