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1. X. Clava-Herculis L. (PRICKLY ASH. ToOTHACHE-TREE.) Small tree, with 
bark armed with warty prickles: branches and (generally) petioles armed with long 
prickles: leaves7 to 9-foliolate ; leaflets ovate-lanceolate, crenate-serrulate: panicles 
terminal: stamens 5: carpels3, nearly sessile. (X. Carolinianum Lam.)—A species of 
the Gulf States which extends into Texas to the 100th meridian. A form occurs in 
Texas with all the leaves3-foliolate. Var. FRUTICOSUM Gray isshrubby, with shorter 
ovate or oblong more strongly crenate leaves, and 2 carpels.—From the Colorado to 
the Rio Grande. 
9. X. Pterota HBK. Small tree or shrub, with zigzag branches armed with short 
curved prickles: petioles winged ; leaflets 7 to 9, small, obovate, coriaceous, crenate 
above the middle: flowers in axillary clusters: stamens 4: ovaries 2, but ripening a 
solitary globose pitted and dotted distinctly stipitate carpel.—A very common shrub 
on the lower Rio Grande, where it is called “colima.” Reputed to have considerable 
medicinal value. 
5. PTELEA L. (SHRUBBY TREFOIL. HOp-TREE. ) 
Shrubs or small trees, with opposite and alternate 3-foliolate leaves, 
greenish-white small polygamous flowers in compound terminal cymes, 
4 or 5 sepals, petals and stamens, and a broadly winged orbicular fruit, 
the wing embracing a slender stipe. 
1. P. angustifolia Benth. Leaflets oblong-lanceolate, somewhat rhomboidal, 2.5 
to 6.5 em. long, acute or acuminate, entire: petals 4 to 6mm. long: fruit 12 to 16mm. 
broad, emarginate at base and often above; stipe narrow, 2 to 4 mm. long.—From 
the Guadalupe to the Rio Grande and extending to the region about El Paso and 
westward. 
9. P. trifoliata L. (Hopr-TrEE.) Like the last, but often more of a tree, with 
broader (ovate) and larger leaves (downy when young), smaller flowers, more broadly 
winged fruit not emarginate at base, and a longer thicker stipe. —Throughout southern 
and western Texas. Var. MOLLIS Torr. & Gray has branchlets, petioles, and lower 
leaf-surfaces clothed with a soft tomentose pubescence even when old.—Throughout 
central and western Texas, where it is the common form. 
6. HELIETTA Tulasne. 
Shrubs with opposite 3-foliolate leaves, terminal and axillary panicles 
of small purplish-white flowers, 3 or 4 sepals, petals and stamens, a 
very small glandular warty ovary, and an obconical fruit which finally 
separates into 3 or 4 samaras (winged fruits). 
1. H. parvifolia Benth. A smooth shrub with grayish bark : leaflets rather pale 
green, oblanceolate to obovate, obtuse, the terminal one much the largest, the lateral 
ones variable in size and sometimes one or both wanting.—A common shrub on the 
blufis of the lower Rio Grande, known as “ barreta.” 
7, AMYRIS P. Browne. (ToRCH-WOOD.) 
Shrubs or trees with mostly alternate 3-foliolate leaves, panicled 
white flowers, 4 sepals and petals, 8 stamens, and fruit a globose 1- 
seeded drupe. 
1. A. parvifolia Gray. A low shrub: leaflets only 12 to 18 mm. long, rhombic- 
ovate or narrower, obtuse, nearly all crenate or crenulate, dull and with rather incon. 
spicuous reticulation ; lateral ones short-petiolate or subsessile, as is sometimes the 
terminal one also. —On the Rio Grande below Brownsville. 
