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The families of flowering plants

L. Watson and M.J. Dallwitz

Alliaceae J.G. Agardh

~ Former Liliaceae, combining Amaryllidaceae-Agapanthoideae and -Allioideae with Asparagaceae-Brodiaeoideae of APG III

Including Agapanthaceae Lotsy, Gilliesiaceae Lindley, Milulaceae Traub, Themideae (Themidaceae) Salisb., Tulbaghiaceae Salisb.

Habit and leaf form. Herbs; laticiferous (mucilaginous, e.g. in Allium), or non-laticiferous; bearing essential oils, or without essential oils. Perennial; with a basal aggregation of leaves (but sometimes the leaves long-sheathed so as to appear cauline); bulbaceous, or cormous (especially ‘Themidaceae’), or rhizomatous (rarely — e.g. Agapanthus). Mesophytic, or xerophytic. Leaves not evergreen; alternate; conspicuously distichous (e.g. leek), or spiral; flat, or rolled, or terete (or angular); sessile (usually), or petiolate (rarely, e.g. Allium ursinum); sheathing. Leaf sheaths with free margins. Leaves aromatic (often onion-scented, with allylic sulphides), or without marked odour; simple; epulvinate. Lamina entire; linear, or lanceolate, or ovate (rarely); parallel-veined, or palmately veined, or pinnately veined (then pinnate-parallel); without cross-venules.

General anatomy. Plants with laticifers (articulated), or without laticifers. The laticifers of Allium, in leaves (in the inner chlorenchyma).

Leaf anatomy. Stomata present; anomocytic. The mesophyll containing crystals, or without crystals (? — ‘raphides sometimes present, sometimes absent’). Minor leaf veins without phloem transfer cells (Allium, Triteleia).

Axial (stem, wood) anatomy. Secondary thickening absent. The axial xylem without vessels.

Root anatomy. Root xylem with vessels; vessel end-walls scalariform and simple (mainly simple, by contrast with Amaryllidaceae).

Reproductive type, pollination. Plants hermaphrodite. Floral nectaries present. Nectar secretion from the gynoecium (from septal nectaries). Pollination entomophilous.

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’ (usually), or solitary (Ipheion); in umbels. The ultimate inflorescence units cymose. Inflorescences scapiflorous; umbellate, usually representing one or more contracted, helicoid cymes; with involucral bracts (the umbel surrounded by (1–)2(to several) bracts, which may be fused); spatheate (with reference to the one to several spathal involucral bracts). Flowers fragrant, or odourless; regular to somewhat irregular. The floral irregularity e.g. in some Allium species, involving the androecium. Flowers 3 merous; cyclic; pentacyclic. Perigone tube present (sometimes predominating, e.g. in Brodiaea), or absent.

Perianth of ‘tepals’; 6; free to joined; 2 whorled (3+3); isomerous; petaloid; similar in the two whorls; white, or violet, or blue, or purple, or yellow, or green and white, or brown and white, or white and red. Tepal apex trichomes (TAT) present (Agapanthus), or absent (Allium, Brodiaea, Ipheion).

Androecium 6. Androecial members adnate (at the base of the tepals, or to the tube); all equal (mostly), or markedly unequal (e.g., Ipheion); free of one another (mostly), or coherent (the filaments sometimes basally cohering in Allium); 2 whorled (3+3). Androecium exclusively of fertile stamens (usually), or including staminodes. Staminodes when present, 3, or 4. Stamens 6 (usually), or 2–3 (e.g. the Gilliesia group, Leucocoryne); isomerous with the perianth (usually), or reduced in number relative to the adjacent perianth; alterniperianthial, or oppositiperianthial (sometimes even when six-stamened — e.g. see Dahlgren et al. 1985, drawings of Tritagma, p. 197); filantherous (the filaments flat). Filaments appendiculate, or not appendiculate. Anthers dorsifixed; dehiscing via longitudinal slits; introrse. Endothecium developing fibrous thickenings. The endothecial thickenings spiral. Microsporogenesis successive. Tapetum glandular. Pollen grains aperturate; 1 aperturate; sulcate; 2-celled.

Gynoecium 3 carpelled. Carpels isomerous with the perianth. The pistil 3 celled. Gynoecium syncarpous; synstylovarious, or eu-syncarpous; superior. Ovary 3 locular. Gynoecium stylate. Styles 1; almost ‘gynobasic’, or apical. Stylar canal absent (mostly), or present (‘Themidaceae’, Agapanthus). Stigmas wet type, or dry type; papillate. Placentation axile. Ovules 1–50 per locule (to ‘many’); campylotropous (usually), or anatropous (e.g. most ‘Themidaceae’); tenuinucellate (mostly), or crassinucellate (e.g. Agapanthus). Embryo-sac development Polygonum-type, or Allium-type. Antipodal cells formed; 3; not proliferating; ephemeral. Hypostase present. Endosperm formation nuclear, or helobial.

Fruit non-fleshy; dehiscent; a capsule. Seeds endospermic. Endosperm oily. Seeds winged (e.g., Agapanthus), or wingless. Seeds without starch. Cotyledons 1. Embryo achlorophyllous (2/5); straight to curved. Testa encrusted with phytomelan; black.

Seedling. Hypocotyl internode absent. Seedling collar not conspicuous. Cotyledon hyperphyll elongated (mostly), or compact; assimilatory (mostly), or non-assimilatory (e.g. in some Allium species); when elongated, more or less circular in t.s. Coleoptile absent. Seedling cataphylls present, or absent. First leaf centric, or dorsiventral. Primary root ephemeral.

Physiology, phytochemistry. C3. C3 physiology recorded directly in Allium. Anatomy non-C4 type (Allium). Inulin recorded (Allium, Gibbs 1974). Cyanogenic (?), or not cyanogenic. Alkaloids absent. Saponins/sapogenins present. Proanthocyanidins absent (12 species). Flavonols present (mostly), or absent (e.g. Agapanthus); kaempferol, or kaempferol and quercetin. Ellagic acid absent. Sieve-tube plastids P-type; type II.

Geography, cytology. Holarctic, Paleotropical, and Neotropical. Temperate, sub-tropical, and tropical. Cosmopolitan, but few in Australasia.

Taxonomy. Subclass Monocotyledonae. Dahlgren et al. Superorder Liliiflorae; Asparagales. APG 3 core angiosperms; Superorder Lilianae; non-commelinid Monocot; Order Asparagales (as a synonym of Amaryllidaceae).

Species 600. Genera 30 (according to Dahlgren et al. 1985, who do not list them all); Agapanthus, Allium, Ancrumia, Androstephium, Behria, Bessera, Bloomeria, Brodiaea, Dandya, Dichelostemma, Diphalangium, Erinna, Garaventia, Gethyum, Gilliesia, Ipheion, Leucocoryne, Miersia, Milla, Milula, Nectaroscordum, Nothoscordum, Milla, Muilla, Pabellonia, Petronymphe, Schickendantziella, Solaria, Speea, Trichlora, Tristagma, Triteleia, Triteleiopsis, Tulbaghia, Zoellnerallium.

General remarks. Fay and Chase (1996) resurrected Themidaceae (subsequently rejected), and transferred Agapanthus to Amaryllidaceae, on the basis of rbcL DNA sequencing. Practical implementation of these and subsequent APG re-circumscriptions involving classical Liliaceae awaits their defence in terms of properly revised, fully comparative family descriptions. The present, compiled descriptions (mainly reflecting the Dahlgren et al, 1985 classification) have Alliaceae differing from Amaryllidacerae sensu stricto (q.v.) in phytochemical, pollen-developmental and seedling characters, as well as in conspicuous characters of inflorescence and floral morphology (two androecial whorls, trilocular gynoecium), endospermic seeds with phytomelan, etc., etc.

Economic uses, etc. Allium spp. supply onions and garlic.


His eyes were green as leeks; -
O Sisters three
Come, come to me!
(‘Midsummer Night’s Dream’, v., 2)

And if the boy have not a woman’s gift
To rain a shower of commanded tears,
An onion will do well for such a shift
(‘Taming of the Shrew’, introd.)

Mine eyes smell onions, I shall weep anon
(‘All’s Well’, v., 3)

Illustrations. • Technical details. • Technical details: Allium. • Allium ampeloprasum var. babingtonii: Eng. Bot. 1531 (1869). • Allium caeruleum : Bot. Reg. xxvi, 51 (1840). • Allium macranthum: Bot. Mag. 110 (1884). • Allium scorodoprasum: Eng. Bot. 1532 (1869). • Allium sphaerocephalon: as A. sphaerocephalum, Eng. Bot. 1533 (1869). • Allium ursinum (B. Ent., 1831). • Allium vineale: Eng. Bot. 1534 (1869). • Bessera elegans: Bot. Reg. 1839, 34. • Ipheion uniflora: as Triteleia uniflora, Bot. Reg. 1921, 1837. • Nectaroscordum siculum: Bot. Reg. 1913 (1836). • Tristagma leichtlinii, as Milla:: Bot. Mag. 102 (1876). • Triteleia (Brodiaea) laxa: Bot. Reg. 1685, 1835.

We advise against extracting comparative information from the descriptions. This is much more easily achieved using the DELTA data files or the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, genera included in each family, and classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG). See also Guidelines for using data taken from Web publications.

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 12th September 2017.’.