Herbs or shrubs, sometimes vines in Asparagus, perennial, mostly geophytic, scapose or caulescent, sometimes woody, from elongate, sometimes tuberous rhizomes, or from scaly or tunicate bulbs, or from solid corms. Leaves only rarely persistent, simple, basal and/or cauline, alternate, opposite, or whorled, herbaceous (scalelike in Asparagus), sometimes sheathing; blade typically narrow and parallel-veined, occasionally broad and/or reticulate-veined. Inflorescences racemose, spicate, paniculate, cymose, umbellate, or with flowers single or paired in leaf axils; bracts 1-several, sometimes involucrate or sheathing, or bracts absent. Flowers usually bisexual, sometimes bisexual and unisexual, or unisexual only, usually pedicellate, occasionally sessile; perianth actinomorphic or zygomorphic, often very showy; tepals 6, distinct or less often connate proximally forming tube that may also bear a corona, usually petaloid and ± equal in 2 whorls of 3, or those of outer whorl narrower, greener, more sepaloid; tepal nectaries often present; stamens 6, rarely 3 or 4, sometimes 3 fertile and 3 staminodial, free or adnate to perianth; filaments slender to dilated, occasionally connate-coroniform and/or with bases dilated to form wings; anthers basifixed with latrorse dehiscence or dorsifixed, versatile, and with introse or extrorse dehiscence, cordate to linear; ovary superior to inferior, (2-)3(-4)-locular, often with septal nectaries, ovules usually several or many per locule; styles 1 or 3(-4); stigmas several and distinct or 1 and capitate. Fruits capsular and loculicidal or septicidal, membranaceous to leathery, or baccate, or dry and indehiscent. Seeds 1-many, often flat and wind-distributed, sometimes thicker and with fleshy elaiosomes. x = 3-27+.

There is no question that the evidence available today (Angiosperm Phylogeny Group 1998; P. J. Rudall et al. 1995; K. L. Wilson and D. A. Morrison 2000) strongly supports extensive dismemberment of A. Cronquist´s (1981, 1988, 1993) very broadly circumscribed Liliaceae. No fewer than 30 segregate families have been recognized, though there is not universal acceptance of all of them, and in some cases their ordinal associations are not yet settled. For the genera of Cronquist´s Liliaceae that are present in the flora, Table 1 summarizes their dispositions among the maximum number of segregate families in recent use. Whether ranked as families or otherwise, these sets of genera represent identifiable lineages that have been variously grouped in recent classifications of the monocots (A. L. Takhtajan 1997; K. Kubitzki et al. 1990+, vol. 3; W. S. Judd et al. 1999; R. F. Thorne 2000; A. B. Doweld 2001). Comments on these assemblages appear below, as well as within the various generic discussions and in the introductory chapter on monocot classification by J. L. Reveal and J. C. Pires at the front of this volume.

Traditionally, Pleea, Triantha, Isidrogalvia Ruíz & Pavón (5 species, South America), Tofieldia, and Harperocallis have been included in the tribe Tofieldieae Horaninow within a polyphyletic Melanthiaceae or Liliaceae sensu lato. However, the vastly different morphologies, anatomies, and cytologies of this lineage (J. D. Ambrose 1975, 1980; M. Takahashi and S. Kawano 1989; R. W. Cruden 1991; P. Goldblatt 1995; M. N. Tamura 1995, 1998b; W. B. Zomlefer 1997c) support its recognition as a separate family, Tofieldiaceae (A. L. Takhtajan 1994b, 1997), in a monotypic order, Tofieldiales (J. L. Reveal and W. B. Zomlefer 1998).

The segregate family Nartheciaceae includes three genera that are present in the flora: Aletris, Narthecium, and Lophiola Ker Gawler (treated under Haemodoraceae herein see p. 47).

Many botanists now consider Trillium and the closely related genera Daiswa Rafinesque, Paris Linnaeus, Kinugasa Tatenaki ex Suto, and Trillidium Kunth (when recognized separately) to constitute the separate family Trilliaceae (R. Y. Berg 1962b; S. Kazempour Osaloo, F. H. Utech, M. Ohara and S. Kawano 1999; S. Kazempour Osaloo and S. Kawano 1999; W. B. Zomlefer 1996). Others (M. W. Chase et al. 2000; W. B. Zomlefer et al. 2001) have defined the Melanthiaceae to include these genera, though the two groups have markedly different morphologies and karyologies.

Most recently, Uvularia has been associated not as before with the Melanthiaceae (J. D. Ambrose 1975, 1980; W. B. Zomlefer 1997b) or the Uvulariaceae of R. M. T. Dahlgren et al. (1985) or the Convallariaceae of A. L. Takhtajan (1980, 1997), but with the east Asian Disporum Salisbury in an expanded Colchicaceae (B. Nordenstam 1998; K. Hayashi et al. 1998).

As defined by A. Cronquist (1981), the Liliaceae contained 'about 280 genera and nearly 4000 species.' In a much more restricted, recent sense, the family was considered to include just 11 genera and perhaps 545 species (R. F. Thorne 2000). Thorne recognized two subfamilies, of which the Medeoloideae (Medeola and Clintonia) have sometimes been segregated as the Medeolaceae (A. L. Takhtajan 1997; A. B. Doweld 2001).

T. B. Patterson (1998), K. Kubitzki et al. (1990+, vol. 3), W. S. Judd et al. (1999), R. F. Thorne (2000), and T. B. Patterson and T. J. Givnish (1998) have recognized Calochortaceae separate from Liliaceae. As circumscribed by Patterson and Givnish, the family includes Calochortus, Prosartes, Scoliopus, Streptopus, and Tricyrtis Wallich (not in the flora). A. L. Takhtajan (1997) distributed these genera among three segregate families: Calochortaceae, Scoliopaceae, and Tricyrtidaceae.

Hesperocallis is currently treated as the sole representative of the segregate family Hesperocallidaceae (H. P. Traub 1972; A. L. Takhtajan 1997). Karyologically and embryologically, Hesperocallis is nearest to Hosta (Hostaceae) and the Agavaceae (M. S. Cave 1948, 1970), and even though their base chromosome numbers are different [x = 24 in Hesperocallis and x = 30 in Hosta and Agavaceae (T. W. Whitaker 1934; D. Satô 1935; S. Sen 1975, F. Maekawa and K. Kaneko 1968; M. N. Tamura 1995)], they share a strongly bimodal karyotype. As well, the pollen grains of Hosta plantaginea and Hesperocallis have similar unibaculate muri (A. Alvarez and E. Köhler 1987). Hosta has long been associated with Hemerocallis and Leucocrinum in the liliaceous tribe Hemerocallideae. However, recent molecular and morphological evidence (M. W. Chase et al. 1996; P. J. Rudall and D. F. Cutler 1995) supports separating these genera-Hemerocallis in the Hemerocallidaceae, Leucocrinum in the Anthericaceae (J. G. Conran 1998), and Hosta in a monotypic Hostaceae (K. Kubitzki 1998b; A. L. Takhtajan 1997; W. B. Zomlefer 1998).

In the past, several taxonomic affinities have been suggested for Androstephium, Bloomeria, Brodiaea, Dichelostemma, Milla, Muilla, Triteleia, and Triteleiopsis (Liliaceae, Amaryllidaceae, Alliaceae), but most recently they have been placed in the resurrected family Themidaceae based on molecular and anatomical evidence (M. F. Fay and M. W. Chase 1996; J. C. Pires 2000; J. C. Pires et al. 2001).

The Liliaceae include numerous important ornamentals such as Amaryllis, Hemerocallis, Hosta, Lilium, Narcissus, and Tulipa. The family is a dominant component in the temperate spring flora, which includes both native and introduced species. Many of the introductions, or cultivars derived from them, are from ecologically equivalent, temperate zones and their naturalization potential is high. Asparagus and Allium have edible species of major economic importance, while numerous other genera (e.g., Convallaria, Ornithogalum, Veratrum, Zigadenus) are highly toxic due to the presence of various alkaloids and cardenolides (G. E. Burrows and R. J. Tyrl 2001).

Several horticultural exotics that have been reported as escaped in the flora (J. T. Kartesz and C. A. Meacham 1999) are not clearly naturalized and are not treated herein. They include: Colchicum autumnale Linnaeus, Gagea fistulosa Ker Gawler, G. villosa (M. Bieberstein) Duby, Gloriosa superba Linnaeus, Kniphofia uvaria (Linnaeus) Oken, Liriope muscari (Decaisne) L. H. Bailey, L. spicatum Loureiro, Lycoris radiata (L´Heritier) Herbert, L. squamigera Maximowicz, Ophiopogon jaburan (Siebold) Loddiges, Sternbergia lutea (Linnaeus) Ker Gawler ex Sprengel, and Tricyrtis hirta (Thunberg) Hooker.