Including Aloaceae (Aloëaceae, Aloeaceae) J.G. Agardh
Habit and leaf form. Herbs (mostly), or shrubs, or ‘arborescent’ (some of the woody forms with trunks up to several metres). Plants succulent, or non-succulent. Perennial; with a basal aggregation of leaves (commonly), or with terminal aggregations of leaves (when woody); rhizomatous (always?). Self supporting. Helophytic, or mesophytic, or xerophytic. Leaves small to very large; alternate; spiral (usually), or distichous; ‘herbaceous’, or leathery, or fleshy, or leathery and fleshy; sessile; sheathing. Leaf sheaths with free margins. Leaves with ‘normal’ orientation; simple. Lamina neither inverted nor twisted through 90 degrees; entire; linear, or lanceolate, or ovate, or subulate (etc.); parallel-veined (but the veins often invisible externally); without cross-venules. Lamina margins entire, or serrate, or dentate (and often with an apical spine). Leaves with a persistent basal meristem, and basipetal development.
Leaf anatomy. Stomata present; on both surfaces; anomocytic, or tetracytic, or paracytic (rarely).
Lamina dorsiventral, or centric. The mesophyll containing mucilage cells (with raphides); containing calcium oxalate crystals. The mesophyll crystals raphides (abundant), or raphides and solitary-prismatic. Minor leaf veins without phloem transfer cells (Asphodelus).
Stem anatomy. Secondary thickening absent, or anomalous (e.g. Aloë); when present, from a single cambial ring. Xylem with vessels (rarely), or without vessels. Vessel end-walls scalariform.
Root anatomy. Roots with velamen (in some genera), or without velamen. Root xylem with vessels; vessel end-walls mostly simple.
Reproductive type, pollination. Plants hermaphrodite (usually). Floral nectaries present. Nectar secretion from the gynoecium (via septal nectaries).
Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in racemes, or in spikes. The ultimate inflorescence unit racemose. Inflorescences scapiflorous; terminal; simple or compound racemes or spikes. Flowers bracteate; small to large; regular to very irregular; when irregular, zygomorphic. The floral irregularity involving the perianth, or involving the perianth and involving the androecium. Flowers 3 merous; cyclic; pentacyclic. Perigone tube present (often, as a long, commonly curved tube), or absent.
Perianth with distinct calyx and corolla, or of ‘tepals’; 6; free, or joined; 2 whorled (3+3); isomerous; sepaloid and petaloid, or petaloid; similar in the two whorls, or different in the two whorls; green, or white, or red, or pink, or yellow, or purple, or purple and brown (not blue or violet).
Androecium 6. Androecial members free of the perianth; all equal, or markedly unequal; free of one another; 2 whorled (3+3). Androecium exclusively of fertile stamens. Stamens 6; diplostemonous; alterniperianthial. Anthers dorsifixed; dehiscing via longitudinal slits; introrse; tetrasporangiate; unappendaged. The endothecial thickenings spiral. Microsporogenesis simultaneous. Pollen shed as single grains. Pollen grains aperturate; 1 aperturate; sulcate; 2-celled.
Gynoecium 3 carpelled. Carpels isomerous with the perianth. The pistil 3 celled. Gynoecium syncarpous; eu-syncarpous; superior. Ovary 3 locular. Gynoecium stylate. Styles apical. Stigmas 1; dry type (usually), or wet type. Placentation axile. Ovules 2–40 per locule (‘2 to rather numerous’); usually arillate; hemianatropous, or anatropous (nearly orthotropous in Aloë and Asphodelus); bitegmic; crassinucellate. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; not proliferating; ephemeral. Synergids hooked (Asphodelus, and with filiform apparatus). Endosperm formation helobial.
Fruit non-fleshy (nearly always), or fleshy (Lomatophyllum); dehiscent; a capsule. Capsules loculicidal. Seeds endospermic. Endosperm oily. Seeds winged, or wingless. Embryo well differentiated. Cotyledons 1. Embryo achlorophyllous (1/1); straight. Testa usually encrusted with phytomelan; black (usually), or grey, or brown (variable in Bulbine).
Seedling. Hypocotyl internode present, or absent. Mesocotyl absent. Seedling collar not conspicuous. Cotyledon hyperphyll compact; non-assimilatory. Coleoptile present, or absent. Primary root ephemeral.
Physiology, biochemistry. Cyanogenic, or not cyanogenic. Arthroquinones detected (Aloë, Asphodeline, Asphodelus, Bulbine, Eremurus, Kniphofia, Simethis); polyacetate derived. Proanthocyanidins absent. Flavonols absent. Ellagic acid absent. Saponins/sapogenins absent. Inulin recorded (Gibbs 1974). CAM. C3 physiology recorded directly in Asphodelus, Bulbine. CAM recorded directly in Aloë, Astroloba, Bulbine, Gasteria, Haworthia, Poellnitzia.
Geography, cytology. Holarctic, Paleotropical, Neotropical, Cape, Australian, and Antarctic. New Zealand. Widespread Old World, clearly centred in southern Africa. X = (6–)7.
Taxonomy. Subclass Monocotyledonae. Superorder Liliiflorae; Asparagales. APG (1998) Monocot; non-commelinoid. APG 3 (2009) Order: Asparagales.
Species about 800. Genera 20–24; Aloë (including Aloinella Lemée), Guillauminia, Lemeea, Asphodeline, Asphodelus, Astroloba, Bulbine, Bulbinella, Bulbinopsis, Chamaealoë, Chortolirion, Eremurus, Gasteria, Haworthia, Jodrellia, Kniphofia, Lomatophyllum, Paradisea (or Hyacinthaceae, or Anthericaceae?), Poellnitzia, Simethis, Trachyandra.
• Aloë brevifolia: Bot. Reg. 996, 1826.
• Habit (Aloë).
• Kniphofia burchellii: as Tritoma, Bot. Reg. 1745, 1836.
• Simethis planifolia: as S. bicolor, Eng. Bot. 1541 (1869).
• Eremurus, Gasteria, Haworthia, Knophofia (Chittenden).