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

1134 TRILLIACEAE/TRILLIUM
purple-flowered plants; they have been segregated as forma luteum J.D. Freeman but are not
formally recognized here. Trillium gracile is very similar to T. ludovicianum and is probably
the “western expression” of that species (Mitchell 1989). However, Mitchell (1989) considered
that there is “sufficient evidence taxonomically to split off T. gracile …” This species differs morphologically
(e.g., plant height, leaf shape, shorter sepals, 3-angled ovary) and flowers 2–3
weeks later (Mitchell 1989). Trillium gracile is also “closely related” to T. viridescens (scapes scabrous)
but can be distinguished by its glabrous scapes (Mitchell 1989). (TOES 1993: V) � m/305
Trillium ludovicianum Harb., (of Louisiana), LOUISIANA TRILLIUM. Plant to 28(–31) cm tall, usually
in very dense clumps; leaf-like bracts lanceolate to broadly ovate, 5–9.5(–10) cm long,
rounded to rarely acute, sessile, usually distinctly mottled, with a metallic sheen; flowers
sessile, with light sweet fragrance (Singhurst et al. 2002b) or odor of carrion (Case 2002); sepals
widely spreading, sometimes with tips reflexed, green, 19–40 mm long; petals divergent-erect,
greenish with purple claw-like bases or purple striations (thus somewhat bicolored) or sometimes
purple throughout, linear-oblanceolate, 35–55 mm long; anthers 7–20 mm long; ovary 6angled;
fruit � 6-angled. Mixed hardwood-pine forests, slopes, typically on rather elevated
ground; Newton, Jasper (BAYLU), and Tyler (Singhurst et al. 2002b) cos. LA, MS, and TX. Collections
of this species from TX have often been misidentified as T. gracile (Singhurst et al. 2002).
Feb–early Apr. While not officially designated as such (e.g., TOES 1993; Carr 2002d; Poole et al.
2002), given its limited distribution in the state, we consider this species to be of conservation
concern in TX. �
Trillium pusillum Michx. var. texanum (Buckley) Reveal & C.R. Broome, (sp.: very small; var.: of
Texas), TEXAS TRILLIUM. Plant to 30 cm tall; leaf-like bracts narrowly lanceolate to elliptic-lanceolate
or oblong, (3–)4–6(–8) cm long, obtuse to rounded, not mottled, sessile or abruptly narrowed
to short petioles, farinose on adaxial surface due to numerous stomata; flowers on conspicuous
erect pedicels, an odor, if present, not known; pedicels 2–4 cm long; sepals spreading,
green, 1.7–3 cm long; petals spreading, white, becoming pink and eventually reddish with age,
narrowly lanceolate to lanceolate, (1.5–)2–2.5(–3) cm long; gynoecium ca. as long as the stamens;
fruit triangular-ovoid, sharply 6-ridged at base of style. Creek bottom bogs (baygalls) at the
head of springs and seeps (Singhurst et al. 2002), acid hardwood bottoms and lower slopes;
Cass, Harrison, Nacogdoches, Wood (BRIT), Cherokee, Rusk, Smith (BAYLU), Houston, Panola
(Freeman 1970), Tyler, (TOES 1993), Jasper (MacRoberts & MacRoberts 1998a), Angelina
(Singhurst et al. 2002b), and Marion (J. Singhurst, pers. comm.) cos. in the Pineywoods; endemic
to nw LA and ne TX (Carr 2001). Mar–May. [T. pusillum Michx. var. texanum (Buckley) C.F.
Reed—a later homonym, T. texanum Buckley] The TEXAS TRILLIUM has been variously treated as
a distinct species (e.g., Correll & Johnston 1970; Hatch et al. 1990; Timmerman-Erskine et al.
2002), a variety of T. pusillum (e.g., Cabe & Werth 1995; Singhurst et al. 2002b), or part of T.
pusillum var. pusillum (Case 2002). Recently, Timmerman-Erskine et al. (2002) argued that
since var. texanum is unique in having both adaxial and abaxial leaf stomata, it should be
treated as a separate species. However, until further work is done on T. pusillum throughout its
entire range, we are following Singhurst et al. (2002b) in recognizing the TEXAS TRILLIUM at the
varietal level. This approach formalizes the relationship with T. pusillum but also recognizes
the morphological distinctiveness of the populations at the extreme sw edge of that species’
range. According to Case (2002), T. pusillum “comprises widely disjunct, regional populations,
each varying somewhat from the others and variable within itself as well.” This is the only Tr illium
taxon in TX with pedicellate flowers (pedicellate species are segregated into subgenus
Phyllantherum). (TOES 1993: V; RARE 2002a: G3T2T3S2S3SOC) �/305
Trillium recurvatum L.C. Beck, (curved backwards), PRAIRIE TRILLIUM, PRAIRIE WAKE-ROBIN. Plant
to 40(–50) cm tall; leaf-like bracts narrowly lanceolate to ovate, 5–11(–18) cm long, acute to
slightly acuminate, usually obscurely mottled, petiolate (the petioles (0.05–)0.1–0.2(–0.3) the total