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

MELANTHIACEAE
739
AA small family (ca. 7–8 genera, ca. 68–93 species) of perennial herbs typically of woodland
and alpine areas from subtropical to temperate and arctic regions of the n hemisphere. Many
Melanthiaceae are characterized by having bulbs or rhizomes, an unusual type of anther dehiscence
(opening as a peltate disk), and shared susceptibility to certain rust fungi (Zomlefer
1997a). The genera have been variously treated in terms of family affiliation. Some authorities
have put them in a very broad and clearly polyphyletic (but practical) Liliaceae (e.g., Correll &
Johnston 1970; Cronquist 1988; Diggs et al. 1999), while others have recognized a smaller but
still rather inclusive polyphyletic Melanthiaceae, including only superficially similar genera
now treated in Nartheciaceae and Tofieldiaceae (e.g., Dahlgren et al. 1985). Still others (e.g.,
Zomlefer 1997a; Tamura 1998b; Judd et al. 1999, 2002) recognized a more narrowly defined
Melanthiaceae (ca. 10-11 genera, 77–119 species), excluding Trillium and related genera (recognized
as the Trilliaceae). The circumscription here is slightly narrower, limited to the tribe
Melanthieae of Zomlefer and Judd (2002), a monophyletic taxon. Some recent molecular and
morphological analyses (e.g., Chase et al. 2000; Fuse & Tamura 2000; Rudall et al. 2000b) support
the inclusion of Trillium and related genera in Melanthiaceae (a circumscription followed
by the Angiosperm Phylogeny Group (APG II 2003). Such a treatment is, however, problematic
for a flora in that it groups together plants of radically different morphologies. As a result, we
are taking what we consider to be an intermediate, though practical, approach in recognizing
the Melanthiaceae excluding the Trilliaceae. For a detailed discussion of the groups formerly
treated as Liliaceae in the broad sense, see the family synopsis of the Liliaceae (here treated in a
restricted sense) on page 726. � Veratrum alkaloids (see further discussion under Veratrum),
some highly toxic, are found in a number of genera, including Amianthium, Schoenocaulon,
Toxicoscordion, Veratrum, and Zigadenus. Amianthium muscitoxicum (Walt.) A. Gray, FLY-POI-
SON (a literal translation of the Latin specific epithet), of the se U.S., sometimes included in
Zigadenus, historically yielded root extracts which were mixed with honey or molasses and
used as an insecticide against houseflies (Zomlefer 1997a). An illegitimate orthographic variant
“Melanthaceae,” has been used by some authors in the past (Zomlefer 1997a). The key to genera
is modified from Zomlefer (1997a) and Zomlefer and Judd (2002). Family name from
Melanthium, a genus of 4 species of e North America, here treated as part of Veratrum. (Greek:
melas, black or dark, and anthos, flower, in reference to the persistent flower parts becoming
dark after flowering) (subclass Liliidae—Cronquist; order Liliales—APG II)
FAMILY RECOGNITION IN THE FIELD: plants scapose or subscapose herbs with numerous small
flowers in racemes, panicles or spikes and ovaries with 3 styles.
REFERENCES: Kupchan et al. 1961; Johnson 1969; Zomlefer 1997a; Tamura 1998b; Frame et al.
1999; Fuse & Tamura 2000; Rudall et al. 2000b; Zomlefer et al. 2001; Zomlefer & Judd 2002;
Zomlefer & Smith 2002.
1. Leaves (actually leaf-like bracts) in a single whorl of 3 at the summit of the stem; flower solitary;
fruits fleshy, berry-like ____________________________________________________ Trillium (see Trilliaceae)
1. Leaves mostly basal, not in a single whorl of 3 at summit of stem; flowers numerous; fruits dry capsules.
2. Inflorescence spicate (with sessile flowers); bulbs covered with dark fibers; tepals 2.3–4.7 mm
long; seeds with a short terminal appendage ____________________________________ Schoenocaulon
2. Inflorescence racemose to paniculate (with stalked flowers); bulbs, if present, not covered
with dark fibers; tepals 3–16 mm long; seeds lacking terminal appendage.
3. Rhizome present, sometimes terminated by a bulb; tepals each with 2 glands at base; inflorescence
floccose pubescent OR glabrous.
4. Rhizome terminated by a tunicate bulb; tepals greenish yellow, aging dark reddish purple;
inflorescence floccose pubescent; seeds broadly winged; plants flowering May–Jul _______ Veratrum
4. Rhizome without a terminal bulb; tepals white to cream colored; inflorescence glabrous;
seeds angled but not winged; plants flowering mid-Jul–Sep ________________________ Zigadenus
3. Rhizome absent, underground stem a bulb (this sometimes slender); tepals each with 1
gland at base or gland lacking; inflorescence glabrous.