BURSERACE.E 645 



slender pubescent petiolule, slightly thickened and revolute on the margins, dark green 

 above, pale pubescent below, ^'-f ' long, about i' wide, with a slender midrib and obscure 

 primary veins. Flowers regular, minute, dioecious, on slender accrescent pubescent 

 pedicels from the axils of ovate minute deciduous bracts, in many-flowered hoary-tomentose 

 racemes 3'-4|' long, the pistillate accrescent, becoming 4'-8' in length; calyx campanulate, 

 5-parted, the lobes ovate, acute, hoary-tomentose on the outer surface; disk 5-lobed; stam- 

 inate flowers appearing sessile in the bud; their pedicels only slightly accrescent; petals 

 filiform; filaments slender, elongated, slightly villose toward the base, inserted between 

 the lobes of the disk and alternate with the calyx-lobes; anthers introrse, 2-celled, united 

 except at apex, opening longitudinally by marginal slits, their connective orbicular, con- 

 spicuous; pistillate flowers on short accrescent pedicels; petals or very rarely present; 

 stamens 0; ovary compressed, unequally 3-angled, villose-hirsute on the margins, 3-celled 

 at base, with two small compressed empty cells, the third larger with two anatropous 

 ovules; styles 2, subulate or recurved, often of unequal length, stigmatic above the middle. 

 Fruit lanceolate, acuminate, narrowly 2-winged, ciliate on the margins with long spreading 

 hairs, slightly tinged with red, f ' in length and about two-thirds as long as its slender 

 hairy pedicel; seeds acute at ends, pale yellow, j' long. 



A slender tree, in Florida occasionally 30 high, with a trunk 6'-8' in diameter, and slen- 

 der branchlets hoary-pubescent during their first year becoming dull red-brow r n, glabrous and 

 marked by numerous small pale lenticels and by the large obovate obcordate scars of fallen 

 leaves showing the ends of three conspicuous equidistant fibro- vascular bundles; in Florida 

 more often a shrub. 



Distribution. Florida, Everglade Keys (Timbo Hummock near Gozman's Homestead, 

 Caldwell's Hummock and Long Key), Dade County; in the Bahama Islands, and in Cuba, 

 southern Mexico, Central America and Argentina. 



XXVHI. BURSERACE^. 



Trees or shrubs, with resinous bark and wood. Leaves alternate, pinnate, without 

 stipules. Flowers perfect or polygamous, in clustered racemes or panicles; calyx 4-5- 

 lobed, the lobes imbricated in the bud, persistent; petals 4-5, imbricated in the bud, dis- 

 tinct or slightly united, deciduous; stamens twice as many as the petals, inserted under 

 the annular or cup-shaped disk; filaments distinct, subulate; anthers introrse, 2-celled, 

 the cells opening longitudinally; pistil of 2-5 united carpels; ovary 2-5-celled; styles united; 

 stigma 2-5-lobed; ovules 2 in each cell, pendulous, collateral, anatropous; micropyle 

 superior; raphe ventral. Fruit drupaceous. Seeds without albumen; seed-coat mem- 

 branaceous: embryo straight; cotyledons foliaceous; radicle short, superior. 



Of the sixteen genera of this family, which is widely distributed through the tropics 

 of the two hemispheres, one only, Bursera, occurs in the United States, reaching the shores 

 of southern Florida with an arborescent species, and southern California and Arizona with 

 another species. 



* 



1. BURSERA Jacq. 



Trees, with balsamic resinous juices. Leaves unequally pinnate; leaflets opposite, 

 petiolulate, entire or subserrate, thin, or coriaceous. Flowers polygamous, small, on 

 fascicled or rarely solitary pedicels, in short or elongated lateral simple or branched 

 panicles; calyx minute, membranaceous; petals inserted on the base of an annular crenate 

 disk, reflexed at maturity above the middle; stamens inserted on the base of the disk; 

 anthers oblong, attached on the back above the base, usually effete in the pistillate flower; 

 ovary sessile, ovoid, 3-celled, rudimentary in the staminate flower; style short; stigma 

 capitate, obtuse, 3-lobed; ovules suspended below the apex from the central angle. Fruit 

 with a valvate epicarp, globose or oblong-oblique, indistinctly 3-angled; flesh coriaceo- 

 carnose, 2-3- valved : nutlets 1-3, usually solitary, adnate to a persistent fleshy axis, 1-celled, 



