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

7. Leaves straight or nearly so, lacking strongly inrolled margins, usually pale bluish to sage
green, conspicuously glaucous, � smooth on both surfaces; leaf margins yellowish, flat
YUCCA/AGAVACEAE
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__________________________________________________________________________ Y. pallida
5. Leaf margins whitish, usually shredding into prominent white fibers (these often disappear-
ing late in year); pistils usually 2–3.2 cm long.
8. Inflorescence usually unbranched and raceme-like or with 1 or 2 short, spreading branches
near base (these often soon deciduous), borne below to just above leaf tips (separated
from them by less than its own length of naked scape) _____________________________ Y. arkansana
8. Inflorescence a much branched panicle, borne well above tips of leaves (separated from
them by nearly its own length or more of naked scape).
9. Leaves very slender, 8–15 mm wide, 100–200 per strikingly globose rosette; fruit usually
constricted near middle; plants of limestone substrates ___________________________ Y. constricta
9. Leaves usually (6–)15–40 mm wide, ca. 50–85 per rosette (rosette not globose in appearance);
fruit constricted or not so; plants of sandy substrates.
10. Inflorescences pubescent (rarely glabrous); fruits usually constricted near the middle;
plants of Pineywoods and Post Oak Savannah ____________________________ Y. louisianensis
10. Inflorescences glabrous; fruits usually not conspicuously constricted; plants of w edge
of Blackland Prairie (Dallas Co.) and westward _________________________________ Y. necopina
Yucca aloifolia L., (with leaves like Aloe, Asphodelaceae), DAGGER PLANT, ALOE YUCCA, SPANISH-
BAYONET. Plant large, to 3(–7) m tall, very variable morphologically; stems 1–3, unbranched or
sparingly branched, often growing parallel to the ground for part of their length; leaves 12–40(–50)
cm long, 2.5–6 cm wide, dark green, rigid, marginally denticulate, rarely with straight fibers;
inflorescences paniculate, glabrous or slightly pubescent; perianth globose, creamy white (can
be tinged with green or purple basally); fruits 3.5–5 cm long, indehiscent, pulpy. Widely cultivated
in East TX, escaping or persisting for decades; old homesteads, dump sites, along railroads,
usually sandy soils but sometimes black clayey soils; Jasper, Liberty, Newton, Tyler, and
Walker (Eric Keith, pers. comm.) cos.; native to the se U.S. from VA s to FL w to coastal TX (but
only naturalized in East TX). Jun–Aug(–fall). [Y. serrulata Haw.] “Yucca aloifolia has been
widely cultivated, and horticultural forms (or varieties, depending upon the source) differ in
the striping of yellow and white on the leaves” (Hess & Robbins 2002). This species is sometimes
mistaken for Y. gloriosa var. recurvifolia, another species of the se U.S. that is also cultivated,
persists, and escapes in east Texas; however, that species has longer (40–100 cm long)
mostly recurved, flexible, usually entire leaves and � leathery fruits.
Yucca arkansana Trel., (of Arkansas), ARKANSAS YUCCA, SOAPWEED. Leaves 20–60(–70) cm long,
10–25 mm wide, the margins at first white, papery with curly fibers; inflorescence glabrous;
perianth 32–65 mm long, greenish white, globose; capsules ca. 4–7 cm long. Rocky limestone or
sandy soils, prairies and hillsides; Pineywoods and Gulf Prairies and Marshes w to Rolling
Plains and e Edwards Plateau; AR, KS, MO, OK, and TX. Mar–mid-May (this is the earliest
bloomer of the dry-fruited Yuccas in Texas—K. Clary, pers. comm.). [Y. angustissima Engelm. ex
Trel. var. mollis Engelm.] The roots, containing saponins, were used as a soap by both Native
Americans and pioneers and the seeds were eaten raw, roasted, or ground into a flour
(Yatskievych 1999). DNA evidence (Clary 1997) suggests that this species is related to Y.
louisianensis. m/307
Hybrids of Y. arkansana and Y. pallida have been found on limestone in Dallas (McKelvey
1947), to the w of East TX at Glen Rose in Somervell Co. (Shinners 1958), and recently in Tarrant
County at Tandy Hills Park (BRIT). This latter population of hundreds of individuals over
a number of acres is quite variable, with individuals ranging from much like typical Y.
arkansana to those much like Y. pallida as well as a full spectrum of intermediates. The plants
vary from having leaves with curly fibers on the margins to not so, from having leaf margins