Family Nolinaceae

Nolinaceae T. Nakai

~ Formerly Agavaceae, APG Asparagaceae-Nolinoideae

Habit and leaf form. Generally ‘arborescent’ (to a few metres tall, with simple or sparingly branched trunks). With terminal aggregations of leaves. Pachycaul. Xerophytic. Leaves alternate (in terminal rosettes); tough and hard or leathery; sessile; sheathing; simple. Lamina entire; linear; parallel-veined.

Leaf anatomy. Stomata with guard-cells rich in oil.

The mesophyll containing calcium oxalate crystals. The mesophyll crystals raphides and solitary-prismatic. Vessels present; end-walls scalariform.

Stem anatomy. Secondary thickening anomalous; from a single cambial ring (cf. Dracaenaceae). Xylem without vessels.

Root anatomy. Root xylem with vessels; vessel end-walls simple (?).

Reproductive type, pollination. Unisexual flowers present. Plants dioecious, or polygamodioecious. Floral nectaries present. Nectar secretion from the gynoecium (from septal nectaries).

Inflorescence, floral, fruit and seed morphology. Flowers aggregated in ‘inflorescences’; in panicles. Inflorescences panicles, often large and many-flowered, the flowers on articulated pedicels. Flowers regular; 3 merous; cyclic. Perigone tube absent. Hypogynous disk absent.

Perianth of ‘tepals’; 6; free; 2 whorled (3+3); isomerous; petaloid (?); similar in the two whorls (?).

Androecium 6. Androecial members free of the perianth; all equal; free of one another; 2 whorled (3+3). Androecium exclusively of fertile stamens. Stamens 6; diplostemonous. Anthers dorsifixed (epipeltate); dehiscing via longitudinal slits. Pollen shed as single grains. Pollen grains aperturate; 1 aperturate; sulcate; 2-celled.

Gynoecium 3 carpelled. Carpels isomerous with the perianth. The pistil 1 celled, or 3 celled. Gynoecium syncarpous; eu-syncarpous; superior. Ovary 1 locular (Dasylirion), or 3 locular. Gynoecium stylate. Styles 1; apical; shorter than the ovary, or about as long as the ovary (‘relatively short’). Placentation when unilocular, basal (Dasylirion); when trilocular, axile (Nolina). Ovules in the single cavity in Dasylirion, 3–6; in Nolina, 2 per locule; anatropous; tenuinucellate. Endosperm formation nuclear.

Fruit non-fleshy (more or less dry, by contrast with Dracaenaceae); indehiscent; capsular-indehiscent, or a samara. Testa without phytomelan; thin.

Seedling. Hypocotyl internode present (short). Seedling collar not conspicuous. Cotyledon hyperphyll compact; non-assimilatory. Coleoptile absent. Seedling cataphylls present. Primary root ephemeral.

Physiology, biochemistry. Not cyanogenic. Alkaloids absent (?). Proanthocyanidins absent. Flavonols present; quercetin. Ellagic acid absent. Saponins/sapogenins present (Nolina).

Geography, cytology. Holarctic and Neotropical. Warm America.

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

Species 45–50. Genera 3–4; Beaucarnea, Nolina, Dasylirion.

Illustrations.
• Dasylirion, young fruit.