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

488 COMMELINACEAE
angled distally; leaves narrowly to broadly elliptic, tapering to broadly rounded at base, (3.5–)
4.5–8 cm long, 1.2–3(–4) cm wide, the margins minutely denticulate; flower 1 per stem; perianth
12–28 mm long, smooth on inner surface; anthers 5–10(–13) mm long; connectives of filaments
barely exserted beyond anthers; ovary stipitate; capsule 8–24 mm long, ellipsoid; seeds arillate.
Deep ravines, mesic forests; Cass (Singhurst 11724, BAYLU), Jasper (Singhurst 11213, BAYLU;
Singhurst et al. 2003a), and Newton (Carr & Wolf 15983, TEX) cos.; se Canada and widespread
in the e U.S. w to ND and TX. Apr–May. [Oakesia sessilifolia S. Wats.; Oakesiella sessilifolia (L.)
Small] The Cass Co. location is disjunct by approximately 280 km from the Newton and Jasper
localities (Singhurst et al. 2003a). The species was first collected in TX by Carr and Wolf in
1997. 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. �
COMMELINACEAE R. Br.
SPIDERWORT FAMILY
Annual or perennial herbs; leaves alternate or basal, with closed, tubular basal sheaths and
broad or narrow, grass-like, entire blades; flowers in small cymose clusters subtended by reduced
upper leaves or leafy bracts (if the bracts enclose the flowers they are referred to as
spathes); sepals 3; petals 3, thin and delicate, usually lasting half a day or less (flowers open during
morning, later in cloudy weather); stamens usually (5–)6, all fertile or some modified into
staminodes (= sterile stamens) or lacking; filaments often long-hairy; pistil 1; ovary superior;
fruit a capsule.
AA medium-sized (ca. 630 species in 40 genera—Faden 2000b) family of tropical, subtropical,
and warm temperate herbs, with greatest diversity in Africa (Faden 1983). It is a well-defined
family characterized by a “closed leaf sheath, a succulent leaf blade, and three-merous flowers
with distinct petals and sepals” (Evans et al. 2000a). A number are widely used as ornamentals,
including species of Tradescantia (SPIDERWORT), Rhoeo (BOATFLOWER, OYSTERPLANT), and
Zebrina (WANDERING-JEW); the latter 2 genera are now typically included in Tradescantia
(Hunt 1986a). The flowers are unusual in lacking nectar and being ephemeral (lasting only a
few hours); the only reward for pollinators is pollen, and a number of specialized pollination
adaptations have evolved (Faden 1998, 2000b, 2000c). These include such attractants as yellow
antherodes (= sterile “anthers” on staminodes), colorful showy hairs on stamens, and broad yellow
connectives, all of which give the impression of more pollen than is actually present (and
thus serve to deceptively attract pollinators) (Faden 1992; Evans et al. 2000b). “Floral deception
is common and is often associated with heteranthery in flowers, which directs bees to the set of
stamens that offers the lesser reward” (Faden 2000c). Pollen dimorphism (= 2 kinds of pollen) is
often associated with heteranthery (= the differentiation of stamens into two sets; e.g., feeding
stamens and pollination stamens). Stamens are sometimes modified into staminodes (which
can be showy), and these in some cases produce sterile pollen (Faden 2000c). Classification
within the Commelinaceae has been confused due to convergent evolution associated with
similar selective pressures relating to the pollination biology of nectarless flowers (Evans et al.
2000a), and there is a high level of incongruence between morphology-based and molecularbased
phylogenies of the family (Evans et al. 2003). Recent molecular evidence indicates that
the family is monophyletic and in general supports the classification of the family developed
by Faden and Hunt (1991), based heavily on anatomical (instead of floral) characters (Evans et
al. 2000b, 2003). According to Faden (1998), there are also differing ideas about the family-level
evolutionary relationships of the Commelinaceae, depending on the types of data used. A variety
of data (except DNA sequence information) suggests a relationship with families such as
Mayacaceae, Xyridaceae, or Eriocaulaceae. However, DNA sequence data place such families as