NYCTAGINACEAE

FOUR O'CLOCK FAMILY

Richard Spellenberg

Perennial, shrub, tree, glabrous or hairy
Stem often forked
Leaves opposite, sessile or petioled, pairs generally unequal; blade generally entire
Inflorescence generally forked; of spikes, clusters, or umbels, each unit sometimes with a calyx-like involucre
Flower bisexual, radial; perianth of 1 whorl, petal-like, bell- to trumpet-shaped, base hardened, tightly surrounding ovary in fruit, lobes 4–5, generally notched to ± bilateral; stamens 1–many; ovary superior (appearing inferior because of hardened perianth base), style 1
Fruit: achene or nut, smooth, wrinkled, or ribbed
Genera in family: 30 genera, 300 species: warm regions, especially Am; some ornamental (Bougainvillea ; Mirabilis , four o'clock).

TRIPTEROCALYX

Perennial from large taproot
Stem much-branched
Leaf petioled; blade < 8 cm, fleshy, margin often wavy
Inflorescence: head; bracts 5–10, green, flowers blooming sequentially across head; receptacle flat to ± conic, studded with peg-like pedicels
Flower: perianth trumpet-shaped, nocturnal, lobes 4–5; stamens 3–5, included; stigma linear, included
Fruit: wings 3–5, wide, continuous above and below fruit body, thin, transparent, conspicuously net-veined
Species in genus: 3 species: arid North America
Etymology: (Greek & Latin: 3-winged cup, from fruit)
[Galloway 1977 Brittonia 27:328–347] Closely related to Abronia.

Native

T. micranthus (Torr.) Hook.

Stem < 6 dm, glandular-sticky or scabrous
Leaf: blade 1–6 cm, narrowly ovate to elliptic, glabrous to glandular-hairy, hairs denser on lower surface
Flower: perianth 6–18 mm
Fruit: wings glabrous except on edges
Ecology: Dunes
Elevation: 800–2450 m.
Bioregional distribution: se Mojave Desert (Kelso, San Bernardino Co.)
Distribution outside California: to Montana, South Dakota, New Mexico
Flowering time: Apr–May
Synonyms: Abronia m. Torr
Horticultural information: TRY.