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

430 ALLIACEAE
to linear or narrowly lanceolate blade portion or blade absent; petioles triangular in cross section;
bracts of inflorescence densely papillose, 3–10 mm long; sepals papillose, appressed to
spreading from fruiting aggregate; petals to ca. 12 mm long; filaments linear to slightly dilated,
ascending, shorter than anthers, glabrous; achenes 1–1.5 mm long; achene beak inserted laterally
above middle of achene, ca. 0.1–0.3 mm long. Swamps, marshes, lake margins, or other wet
areas; Pineywoods and Post Oak Savannah; also Gulf Prairies and Marshes and e Edwards Plateau;
Hatch et al. (1990) also indicated occurrence in the Blackland Prairie (however, we have
seen no confirming specimens from the Blackland Prairie); AR, LA, MS, OK, and TX. Mar–Nov.
Wooten and Brown (1983) studied the reproductive biology of this monoecious species.
Sagittaria platyphylla (Engelm.) J.G. Sm., (broad-leaved), DELTA ARROWHEAD. Leaf blades lanceolate
to elliptic or ovate, 8–20 cm long, 2–8 cm wide, rarely with a lateral projection(s) from
the base, but never truly sagittate; bracts of inflorescence smooth, basally connate, 3–8 mm
long; stalks (pedicels) of fruiting “heads” spreading to recurved; sepals 4–6 mm long, usually
reflexed from fruiting aggregate; filaments dilated, as long as or longer than anthers, pubescent;
achenes 1.2–2 mm long; beak of achene inserted laterally, 0.3–0.6 mm long, horizontal to ascending,
subulate. Swamps, marshes, ponds, or other wet areas; Pineywoods and Gulf Prairies
and Marshes w to Rolling Plains and Edwards Plateau; e U.S. from VA s to FL w to KS and TX.
Apr–Oct. [S. graminea Michx. var. platyphylla Engelm.] This is one of the most common
Sagittaria species in East TX. While not problematic in its native North America, this species
has recently (Sage et al. 2000) been discovered as an introduced weed in w Australia, where it
has been described as an aquatic weed threat and has been designated a “Declared Plant” of the
highest priority for control. m/297
ALLIACEAE Batsch ex Borkh.
ONION FAMILY
Ours perennial, scapose herbs from a bulb, usually but not always with an onion or garlic odor;
leaves usually all basal or subbasal (or nearly to the middle of the stem in some introduced species),
with closed, tubular, basal sheaths and slender blades; inflorescence terminating a scape,
with a basal involucre of one or more sheathing bracts; flowers in umbellate or head-like clusters
or solitary, radially symmetrical; tepals 6, separate or partly connate, all petal-like; stamens
6; ovary superior; style 1; fruit a loculicidal capsule.
A-A medium-sized family of 13 genera (all small except Allium, the other 12 genera totaling
ca. 75–82 species) and ca. 600 species (Rahn 1998a)—but see note under Allium. They are perennial
herbs usually with a bulb (some species in other areas have a rhizome or corm). Most of the
genera are found in South America, but the largest genus, Allium, is widespread in the n hemisphere
(Rahn 1998a). A number are used as ornamentals (e.g., Allium, Ipheion) or as food plants
(e.g., Allium). Raphides or allylic sulphides (which account for the onion smell) are often
present in Alliaceae. Alkaloids are absent but are regularly found in the Amaryllidaceae (Rahn
1998a), within which this family has sometimes been placed. The genera have been variously
treated in terms of family affiliation. Many authorities have put them in a broadly defined and
clearly polyphyletic (but practical) Liliaceae (e.g., Correll & Johnston 1970; Cronquist 1988;
Diggs et al. 1999) based on superficial similarities of the flower structure to that of the genus
Lilium, while others (e.g., Hutchinson 1934; Traub 1963a) treated them in the Amaryllidaceae
based on such characters as the umbellate inflorescence subtended by bracts. However, based
on phylogenetic analyses (e.g., Fay & Chase 1996; Fay et al. 2000), we are following many recent
authors (e.g., Rahn 1998a) in recognizing the Alliaceae as a distinct family; it is apparently a
monophyletic group in the order Asparagales, closely related to the Amaryllidaceae. As such, it
is more closely related to other Asparagales families such as Hypoxidaceae, Iridaceae, and
Orchidaceae than it is to other taxa often put in a broadly defined Liliaceae (Chase et al. 1995a,