keys to the vascular plants of east texas - Botanical Research ...

JUNIPERUS/CUPRESSACEAE
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allergens in East TX. JUNIPERS are troublesome near apple trees and native hawthorns
(Crataegus species) since they serve as an alternate host for cedar apple rusts
(Gymnosporangium spp.). The sweet seed cones of some species were used as a food by Native
Americans, including in the making of pemmican, a jerky-like product; however, large amounts
may have toxic effects (Burrows & Tyrl 2001). Due to fire suppression and other human-induced
changes, a number of native species of Juniperus have become troublesome invaders of
native rangelands, currently affecting millions of acres (Adams et al. 1998). (Latin: juniperus,
name for JUNIPER)
REFERENCES: Hall 1952; Adams 1972, 1975, 1977, 1986, 1993, 2000a, 2000b; Flake et al. 1978;
Owens 1996; Adams et al. 1998; McLemore 2001; McLemore et. al 2004.
1. Mature ovulate cones (seed cones) reddish or copper-colored; leaf gland often with white crystalline
exudate; hilum (= attachment scar) covering seed ca. 1/2 its length ____________________ J. pinchotii
1. Mature ovulate cones blue to bluish black or bluish purple; leaf gland without exudate; hilum
covering seed ca. 1/3 or less it length.
2. Plant usually with one main trunk from base; abaxial (= on side away from twig) leaf glands
usually elliptic to elongate, usually not conspicuously raised (use a 10X hand lens); leaf margins
entire, smooth (under a dissecting scope); species widespread and abundant in East TX
____________________________________________________________________________ J. virginiana
2. Plant usually with several trunks from near base; abaxial leaf glands usually roundish in outline,
often conspicuously raised (use a 10X hand lens); leaf margins irregularly very minutely
cellular-serrulate or cellular-denticulate (under a dissecting scope), not smooth; species known
in East TX only from w margin of area __________________________________________________ J. ashei
Juniperus ashei J. Buchholz, (for its discoverer, William Willard Ashe, 1872–1932), MOUNTAIN-
CEDAR, ASHE’S JUNIPER, ROCK-CEDAR, POST-CEDAR, MEXICAN JUNIPER. Large shrub or small tree to
ca. 6 m tall, usually with several trunks from near base, not resprouting after cutting or burning;
bark ashy-gray to brown; ovulate cones mostly 7–8.5 mm long when mature, dark blue,
glaucous, sweet, resinous; seeds 1(–3), covered by hilum for 1/3 their length. Rocky soils; often
forming thickets or “cedar brakes” (further s and w in TX), Travis, Williamson (TEX), Dallas
(BRIT), Bexar, Bell, Hays, McLennan (BAYLU), and Comal (Turner et al. 2003) cos. on the w margin
of East TX; primarily Cross Timbers and Prairies and Edwards Plateau; AR, MO, OK, and
TX. Due to fire supression, this species currently covers much more area (e.g., in the Cross Timbers
and Prairies) than previously (Hall 1952; Fuhlendorf & Smeins 1997). In fact, Owens (1996)
indicated that in central Texas J. ashei was previously confined to steep slopes, rocky outcrops,
and waterways. This human-induced expansion of J. ashei has significant negative impacts on
other native plants and is problematic for ranchers. Juniperus ashei is sometimes distinguished
with difficulty from J. virginiana; in addition to the characters in the key, J. ashei usually has
stiffer twigs and more odoriferous herbage. Hybridization and introgression have been reported
where the 2 occur together (Correll 1966b; Hall 1952); Hall (1952) also noted that J. ashei can
hybridize with J. pinchotii. However, Adams and Turner (1970) and Adams (1977) indicated
that they refuted these reports of hybridization “using numerous chemical and morphological
characters” (Adams 1993)—they found no evidence of hybridization between J. ashei and either
J. pinchotii or J. virginiana. Nonetheless, Caren McLemore and Bob O’Kennon (pers. comm.)
have observed several colonies of junipers in North Central TX that have morphological characteristics
indicative of hybridization between J. ashei and J. virginiana.
Juniperus pinchotii Sudw., (for botanist Giffard Pinchot, 1865–1946), RED-BERRY JUNIPER,
PINCHOT’S JUNIPER. Large shrub or shrub-like small tree to ca. 6 m tall, usually with several
trunks from near base, resprouting after cutting or burning; bark ashy-gray to brown; ovulate
cones 6–10 mm long, reddish or copper-colored, usually not glaucous or only slightly so, sweet,
not resinous; seeds 1–2, covered by hilum for ca. 1/2 their length. Gravelly or rocky soils, com-