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

728 LILIACEAE
AAs treated here in a restricted sense, the Liliaceae is a medium-sized family of 11 genera and
ca. 550 species (Tamura 1998a) of bulbose or rhizomatous perennial herbs widely distributed in
the n hemisphere, but particularly abundant in temperate Eurasia. Molecular evidence indicates
that the Liliaceae (in the narrow sense) is monophyletic (Patterson & Givnish 2002).
The Liliaceae “…has probably been used in a wider range of circumscriptions than any other
family name” (Fay & Chase 2000). Indeed, taxonomically treating the species that have been
considered to broadly fall within this family (4,950 species in 288 genera—Mabberley 1997)
presents interesting problems. Many authors (e.g, Cronquist 1988) “placed most petaloid monocots
with six-stamened flowers into a very broadly circumscribed—and obviously polyphyletic—Liliaceae”
(Judd 1997). Other authorities separated them into two families, Liliaceae (species
with superior ovaries) and Amaryllidaceae (species with inferior ovaries). However, in the
words of Cochrane and Iltis (2000), such a restricted Liliaceae is “distinguished arbitrarily from
the Amaryllidaceae.” Still other systematists, following such works as Dahlgren et al. (1985),
have divided the group into as many as 40 smaller families. “Recent studies have resulted in
some exciting reevaluation of monocot phylogeny, particulary of the ‘petaloid lilioid monocots’—so
named because these plants have conspicuous petaloid tepals and, therefore, superficially
resemble true lilies. …” (Zomlefer 1999). In fact, recent molecular studies (e.g., Chase et al.
2000) have shown that species traditionally placed in the Liliaceae should be placed in numerous
families in at least four orders, Liliales, Asparagales, Tofieldiales, and Nartheciales. Surprisingly,
former Liliaceae such as Allium, Asparagus, Hemerocallis, Hypoxis, and Polygonatum are
now thought to be more closely related to such families as Iridaceae and Orchidaceae (and
other members of order Asparagales) than to Lilium (Chase et al. 1995a, 1995b, 1996, 2000; Fay
et al. 2000). In the interest of nomenclatural stability, Diggs et al. (1999) followed Cronquist
(1981, 1988, 1993), Kartesz (1994, 1999), and the then unpublished Flora of North America Volume
26 in treating the Liliaceae broadly to include plants now known to be in many different
families. Recognizing the importance of nomenclatural stability, it is with some trepidation
that we now divide up the Liliaceae (in the broad sense). However, it has become quite clear that
parallel and convergent evolution in morphological characteristics (e.g., flower structure) have
been significant factors in obscuring understanding of the actual relationships of “petaloid lilioid
monocots.” In particular, concerted convergence (= convergence in several different traits, favored
by the same shared set of ecological conditions) has been important in hindering an understanding
of phylogenetic relationships in the group (Patterson & Givnish 2002). The phylogeny of the
Liliaceae (in the broad sense) now seems much more settled (e.g., Chase et al. 1995a, 2000; Judd
1997; Judd et al. 1999, 2002; Rudall et al. 2000b; Vinnersten & Bremer 2001), and to retain such a
dramatically polyphyletic family would obscure our knowledge of the evolution of the moncots.
The Liliaceae is thus herein treated in a much less inclusive sense. East TX species that would
traditionally have been included in a broadly considered Liliaceae are here recognized in 16
families in four orders: Asparagales (Alliaceae, Alstroemeriaceae, Amaryllidaceae, Anthericaceae,
Asparagaceae, Convallariaceae, Hemerocallidaceae, Hyacinthaceae, Hypoxidaceae,
Themidaceae), Liliales (Colchicaceae, Liliaceae, Melanthiaceae, Trilliaceae), Nartheciales
(Nartheciaceae), and Tofieldiales (Tofieldiaceae). In order to assist in the identification of plants
previously treated in the lily family in the broad sense, a chart and a key are provided below.
The chart alphabetically lists all genera typically included in the lily family in the broad sense
and indicates the families in which they are now recognized. The key allows identification to
current family for all plants previously included in the broadly conceived lily family. In addition,
two other families, Nolinaceae and Smilacaceae, considered by some authors a number of
decades ago to be in the Liliaceae, are recognized as separate families here. It should be noted
that nomenclature in the petaloid lilioid monocots is still far from settled, with different authorities
drawing family boundaries quite differently. For example, the Angiosperm Phylogeny
Group (APG II 2003) recently proposed combining numerous morphologically quite different
groups (e.g., Agavaceae, Hyacinthaceae, Nolinaceae) into a very broadly conceived Asparagaceae.