LOASACEAE

LOASA FAMILY

Barry Prigge

Annual to shrub; hairs needle-like, stinging, or rough
Leaves alternate in CA, generally ± pinnately lobed; stipules 0
Inflorescence various
Flower bisexual, radial; sepals generally 5, generally persistent in fruit; petals generally 5, free or fused to each other or to filament tube; stamens 5–many, filaments thread-like to flat, sometimes fused at base or in clusters; petal-like staminodes sometimes present; pistil 1, ovary inferior, chamber generally 1, placentas generally 3, parietal, style 1
Fruit: generally capsule (utricle)
Seeds 1–many
Genera in family: 15 genera, ± 200 species: especially Am (Africa, Pacific)
Reference: [Ernst & Thompson 1963 J Arnold Arbor 44:138–142]

MENTZELIA

BLAZING STAR

Annual to shrub; hairs generally barbed-rough (smooth)
Leaf linear to ovate, generally ± lobed; basal in rosettes, generally petioled; cauline generally sessile, ± reduced upward
Inflorescence: generally cyme (or flower 1); bract generally 1 per flower, generally green
Flower: sepals lanceolate to deltate, generally persistent; petals 5, free, generally yellow; stamens generally many, ± free, generally unequal, inner filaments generally thread-like; staminodes 0 or 5–many, outer often petal-like; ovary generally cylindric, placentas generally 3, style thread-like, stigma 3-furrowed or -lobed
Fruit generally tapered to base, sometimes curved
Seeds generally many, grain- to prism-like (triangular in X -section), angled, or lenticular and winged (important to identification)
Species in genus: ± 50 species: w US, ± tropical Am
Reference: [Darlington 1934 Ann Missouri Bot Garden 21:103–226]

Native

M. tridentata (Davidson) H.J. Thomps. & J.E. Roberts

Annual, 10–25 cm, spreading to erect
Leaf 1–9 cm, wavy or toothed
Inflorescence: bract lanceolate to widely ovate, sessile, 2–10-toothed, base sometimes whitish
Flower: sepals 5–13 mm; petals 10–40 mm, cream-white; stamens 6–15 mm, filaments 2-toothed at tip, teeth linear, anther stalk between teeth 1–1.5 mm (generally > teeth), thread-like; style 9–12 mm
Fruit 9–18 mm, 5–8 mm wide, cylindric to barrel-shaped, generally pedicelled, erect to reflexed
Seed 1.5–2.5 mm, narrowed above and below middle, beaked, minutely papillate, whitish
Chromosomes: n=10
Ecology: Creosote-bush scrub
Elevation: 700–1000 m.
Bioregional distribution: c Mojave Desert
Flowering time: Apr–May
Synonyms: M. tricuspis var. brevicornuta I.M. Johnst
Horticultural information: TRY.