BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Yucca Brevifolia (Joshua Tree)
GENERAL BOTANICAL CHARACTERISTICS :
Joshua tree is a large, erect, evergreen, arborescent monocot. It is generally single-stemmed, but plants with two or three stems also occur. Joshua tree is the largest nonriparian plant of the Mohave Desert, reaching heights of 16 to 49 feet (5-15 m); the huge reddish-brown to gray trunks can grow to 2 or 4 feet (0.6-1.2m) in diameter. Erratic branching generally begins 3 to 10 feet (1-3 m) above the ground and is often caused by the yucca-boring weevil which destroys the growing tips. Branches are erect, ascending or spreading, and form a dense, compact, rounded top. The soft, corklike bark is rough and fissured. The inflorescence is a crowded, brittle often glabrous panicle. Globose flowers are greenish-white or gray and papery at maturity, with an odor described as "unpleasantly mushroom-like".
The exact age of Joshua trees may be difficult to determine since annual rings are not produced. The overall shape, however, can provide a general range. Juvenile Joshua trees are generally unbranched; middle-aged plants are forked and dense. Older trees generally have a single stem and an open crown.
Varieties: Important differences in morphology and general growth form of varieties are as follows:
var. brevifolia - tall, stout stem, branches mostly 3 to 10 feet (1-3 m) above the ground.
var. jaegeriana - smaller, 10 to 20 feet (3-6 m) tall, branches mostly 2.3 to 3.3 feet (7-10 dm) above ground, more compact.
var. herbertii - many stems forming clumps up to 33 feet (10 m) in diameter, long rhizomes.
GENERAL BOTANICAL CHARACTERISTICS
REGENERATION PROCESSES
SITE CHARACTERISTICS
SUCCESSIONAL STATUS
SEASONAL DEVELOPMENT
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