Lilioideae genera are relatively homogeneous and distinct from the other two Liliaceae subfamilies (Calochortoideae and Streptopoideae). They are perennial herbaceous flowering plants that are mainly bulbous (Lilieae) with contractile roots, but may be rhizomatous (Medeoleae). Stems unbranched, leaves with parallel venation. Flowers are large and showy. The embryo sac (megagametophyte) is of the Fritillaria-type (tetrasporic). Capsule septicidal, seeds often flattened, exotesta palisaded or lignified. The seeds of Medeoleae are striate. Chromosome number may be 7 (Medeoleae), 9, or 11–14, with a highly variable length (2.2 - 27 µm).
