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

420 AGAVACEAE/YUCCA
Austin Chalk, Hill, McLennan (BRIT), Bell, Williamson, and Travis (Turner et al. 2003) cos.);
mainly Cross Timbers and Prairies; endemic to TX (Kartesz 1999; Carr 2002b, 2002c). May–Jun.
According to Clary (1997), DNA evidence suggests a close relationship of this species with Y.
rupicola. Plants apparently intermediate between Y. pallida and Y. rupicola are found in several
localities (McKelvey 1947), including the area n of Austin (E. Keith, pers. comm.). They usually
have blue-green glaucous leaves (like Y. pallida), but the leaves are twisted and have wavy margins.
E m/308
Yucca rupicola Scheele, (growing on cliffs or ledges), TEXAS YUCCA, TWIST-LEAF YUCCA. Similar to
Y. pallida; colonies typically with 2–15 rosettes; leaves � 100 per rosette, 20–60 cm long, to 40
mm wide, flaccid, twisted, the margins wavy; panicle glabrous to slightly pubescent; perianth
segments whitish or greenish white; stigma lobes widely spreading. Limestone ledges, plains;
Bexar, Comal, Hays, McLennan, Travis, and Williamson (Turner et al. 2003) cos. near w margin
of the Blackland Prairie; mainly Edwards Plateau; endemic to TX (Kartesz 1999; Carr 2002b,
2002c). Apr–Jun. E m/308
Yucca torreyi Shafer, (for John Torrey, 1796–1873, American botanist, physician, and collector of
many w North American plants), TORREY’S YUCCA, SPANISH-DAGGER. Plant large, to ca. 7 m tall;
stems unbranched or rarely with 2–3 branches; dead leaves reflexed on trunk below leaf crown;
leaves 30–110 cm long, light green, stiff, spear-like, entire, with marginal fibers, the apical portion
of the leaves usually rolled inward so that the margins nearly touch; panicle with 0.1–0.5 of
its total length extending beyond the leaves or rarely entirely within the leaves; perianth
subglobose or campanulate, sometimes fully expanding, cream (can be tinged with purple);
fruits 7–14 cm long, indehiscent, fleshy. Gravelly soils, grassy and chaparral mesas and slopes;
Bexar (Turner et al. 2003) and Travis (Carr 2002a) cos. near the sw margin of East TX; also
Brown and Burnet (HPC) cos. on sw margin of the Cross Timbers and Prairies; however, K. Clary
(pers. comm.) questions whether the species is native as far e as Burnet and Travis cos.; mainly
Edwards Plateau and Trans-Pecos. Late Mar–May. [Y. baccata Torr. var. macrocarpa Torr., Y.
crassifolia Engelm., Y. macrocarpa (Torr.) Coville] This species is sometimes treated as a synonym
of the related Y. treculeana (e.g., Powell 1988; Hess & Robbins 2002); according to Webber
(1953) and Correll and Johnston (1970), the two sometimes hybridize. Since they can usually be
readily distinguished in the field, we are following McKelvey (1938), Jones et al. (1997), and
Kartesz (1999) in recognizing them at the specific level.
Yucca treculeana Carr., (for A.A.L. Trécul, 1818–1896, who took plants of this species to France in
1850—Vines 1960), SPANISH-DAGGER, SPANISH-BAYONET, TRECUL’S YUCCA, DON QUIXOTE’S-LANCE,
PITA, PALMA PITA, PALMA DE DÁTILES, PALMA LOCA, TEXAS-BAYONET. Plant large, to ca. 7 m tall;
stems few-branched, with leaf crown at apex; dead leaves reflexed on trunk below leaf crown
(trunks bare of dead leaves on old plants); leaves 50–100 cm long, green, entire (sometimes denticulate
at base of leaf), without marginal fibers, the apical portions of the leaves not inrolled;
panicle with ca. 0.5–0.75 of its total length extending beyond the leaves; perianth broadly globose
or hemispherical, greenish cream to cream (can be lightly tinged with purple); fruits 5–11.5
cm long, indehiscent, the flesh sweetish and succulent. Brushland; Bexar (TAES), Goliad
(TAMU), Hays (TAMU), Travis (Tharp letter quoted in McKelvey 1938; R. O’Kennon, pers. obs.),
and Comal (Turner et al. 2003) cos. near extreme sw margin of East TX, also Brazos Co. (K.
Clary, pers. comm.); s TX n to s part of Cross Timbers and Prairies (Burnet Co.—Buckley in
McKelvey 1938; R. O’Kennon, pers. obs.) and s part of East TX; in the U.S. known only from TX.
Feb–Apr. [Y. treculeana var. succulenta McKelvey] Carr (2002a) considered Travis Co. collections
previously thought to be of this species to be Y. torreyi; however, K. Clary (pers. comm.) observes
that Y. treculeana does come as far e as Travis Co. and also up from s TX to Brazos Co. The
spines were used historically to jab a snake bite and induce bleeding in order to flush away the
poison (Vines 1960). Pioneers cooked and prepared the flowers like cabbage and also pickled
them (Schulz 1922; McKelvey 1938; Crosswhite 1980). According to Havard (1896), the fleshy,