Habit and leaf form. Shrubs, or lianas, or herbs. Switch-plants; with the principal photosynthesizing function transferred to stems (as represented by axillary clusters of cladodes). Leaves much reduced (to small bractlike structures). The herbs perennial; with neither basal nor terminal aggregations of leaves; rhizomatous. Self supporting, or climbing; the climbers stem twiners; twining anticlockwise (Asparagus). Leaves alternate; membranous (scales); more or less sheathing; simple. Lamina entire; parallel-veined. Leaves exstipulate.
Leaf anatomy. The mesophyll commonly containing mucilage cells (with raphides); commonly containing calcium oxalate crystals. The mesophyll crystals raphides. Vessels absent.
Stem anatomy. Secondary thickening absent. Xylem with vessels. Vessel end-walls scalariform. Sieve-tube plastids P-type; type II.
Root anatomy. Roots with velamen (often), or without velamen. Root xylem with vessels; vessel end-walls simple.
Reproductive type, pollination. Plants hermaphrodite, or monoecious, or dioecious, or polygamomonoecious. Female flowers with staminodes (i.e. with nonfunctional stamens). Floral nectaries present. Nectar secretion from the gynoecium (via septal nectaries).
Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’; in cymes, or in racemes, or in umbels. The ultimate inflorescence unit probably cymose. Inflorescences umbel-like or racemelike, but probably always determinate?. Flowers small; regular; 3 merous; cyclic. Perigone tube present, or absent. Hypogynous disk absent.
Perianth of ‘tepals’; 6; free, or joined; 2 whorled; isomerous; sepaloid, or petaloid; similar in the two whorls; green, or white, or yellow.
Androecium 6. Androecial members adnate (at the base of the perianth); free of one another; 2 whorled. Androecium exclusively of fertile stamens (in male and hermaphrodite flowers). Stamens 6; diplostemonous. Anthers dorsifixed; dehiscing via longitudinal slits; introrse. The endothecial thickenings spiral. Microsporogenesis successive. Pollen grains aperturate; 1 aperturate; sulcate; 2-celled.
Gynoecium 3 carpelled. Carpels isomerous with the perianth. The pistil 3 celled. Gynoecium syncarpous; synstylovarious to eu-syncarpous; superior. Ovary 3 locular. Gynoecium stylate. Styles 1; apical; shorter than the ovary to about as long as the ovary (usually rather short). Stylar canal present. Stigmas wet type, or dry type. Placentation axile. Ovules 2–12 per locule; non-arillate; hemianatropous, or anatropous, or orthotropous; crassinucellate. Embryo-sac development Polygonum-type. Endosperm formation nuclear.
Fruit fleshy; indehiscent; a berry. Seeds endospermic. Endosperm oily. Embryo well differentiated. Cotyledons 1. Embryo achlorophyllous (1/1); straight, or curved. Testa encrusted with phytomelan, or without phytomelan (?); ‘often' black.
Seedling. Hypocotyl internode present (short). Seedling collar not conspicuous. Coleoptile absent. Seedling cataphylls present. Primary root persistent.
Physiology, biochemistry. Not cyanogenic. Alkaloids absent. Proanthocyanidins absent. Flavonols present, or absent; kaempferol, or kaempferol and quercetin. Ellagic acid absent. Arbutin absent. Saponins/sapogenins present (steroidal). C3. C3 physiology recorded directly in Asparagus. Anatomy non-C4 type (Asparagus).
Geography, cytology. Holarctic, Paleotropical, Cape, and Australian. Temperate, sub-tropical, and tropical. Widespread, especially Old World.
Taxonomy. Subclass Monocotyledonae. Superorder Liliiflorae; Asparagales. APG (1998) Monocot; non-commelinoid. APG 3 (2009) Order: Asparagales.
Species about 370. Genera 1, or 3; Asparagus, Hemiphylacus(?), Myrsiphyllum, Protasparagus.
Economic uses, etc. Cultivated ornamentals, and culinary asparagus (A. officinalis).
• Technical details: Asparagus.
• Asparagus officinalis (B. Ent.).
• Asparagus officinalis: Eng. Bot. 1515 (1869).