122 



TREES OF NORTH AMERICA 



abruptly enlarj^ed base, imbranched or divideU into several short branches, and 

 covered above by a thick thatch of the pendant dead leaves of many seasons; fre- 

 quently smaller and until ten or twelve years old clothed from the ground with 

 erect living leaves. Bark near the base of old trees dark reddish brown, ^'-^' thick, 

 broken on tlie surface into small thin loose scales. 



Distribution. Common on the high desert plateau of southwestern Texas. 



2. Fruit with thin dry Jlesh, 



7. Yucca arborescens, Trel. Joshua Tree. 



Leaves 5'-8' or on young plants rarely 10'-12' long, \'-\' wide, rigid, crowded 

 in densely imbricated clusters, lanceolate, gradually tapering from the bright red- 

 brown lustrous base, bluish greeu and glaucous, smooth or slightly roughened, con- 



P'^. 107 



cave above the middle, with sharp dark brown points, and thin j^ellow margins 

 armed with sharp minute teeth; persistent for many years. Flowers appearing 

 from March until the beginning of May, the creamy white closely imbricated bracts 

 of the nearly sessile pubescent panicle forming before its appearance a conspicuous 

 cone-like bud 8' or 10' long ; perianth globose to oblong, l'-2' long, greenish white, 

 waxy, dull or lustrous, its segments slightly united at the base, keeled on the 

 back, thin below the middle, gradually thickened upward into the concave incurved 

 rounded tip, those of the outer rank rather broader, thicker, and more prominently 

 keeled than those of the inner rank, glabrous or pubescent; stamens about half as 

 long as the ovary, with filaments villose-papillate from the base; ovary conical, 

 3-lobed above the middle, bright green, with narrow slightly developed septal nectar- 

 glands and a sessile nearly equally 6-lobed stigma. Fruit ripening in May or June, 

 spreading or more or less pendant at maturity, oblong-ovate, acute, slightly 3-angled, 

 2'-4' long, l^'-2' broad, light red or yellow-brown, the outer coat becoming dry and 

 spongy at maturity; seeds nearly ^ long, rather less than y^' thick, with broad 

 well-developed margins to the rim and large conspicuous hilums. 



A tree, 30-^0 high, with a trunk 2-3 in diameter, rising abruptly from a 

 broad thick basal disk, stout tough roots descending deeply into the soil, and stout 

 branches spreading into a broad, often symmetrical head formed by the continued 

 forking of the branches at the base of the terminal flower-clusters; until 8-10 



