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Hill country silverbush

narrowleaf silverbush

Habit Herbs, perennial, monoecious or dioecious, to 5 dm. Herbs or subshrubs, perennial, monoecious or dioecious, to 10 dm.
Stems

erect to ascending, hairy, hairs malpighiaceous.

erect, hairy, hairs silvery or not, malpighiaceous.

Leaves

stipules deciduous, linear-lanceolate, to 1 mm, margins not glandular;

petiole absent;

blade elliptic, 1.5–4 × 0.6–2 cm, margins entire, without glands, surfaces hairy, hairs malpighiaceous.

stipules persistent, subulate, 0.5–1.3 mm, margins not glandular;

petiole 1–3 mm;

blade lanceolate to ovate, 1–4.5 × 0.4–1.4 cm, margins usually entire, rarely serrulate, without glands, surfaces hairy, hairs silvery or not, malpighiaceous.

Inflorescences

unisexual, 3–8 cm;

bracts linear-lanceolate, 2–4.5 mm, margins without glands.

bisexual or unisexual, 0.4–1.3 cm;

bracts ovate to elliptic, 1–2 mm, margins without glands.

Flowers

without pink dye when wetted.

without pink dye when wetted.

Staminate flowers

sepals lanceolate to narrowly elliptic, 4–5.5 × 1.1–1.4 mm;

petals cuneate-elliptic to cuneate-obovate, 3.3–4 × 1.6–3 mm, free from androphore;

nectary glands oblong, 0.4–0.5 × 0.3–0.4 mm, adnate to androphore, glabrous;

stamens 10, staminodes 0.

sepals lanceolate, 2–3 × 0.5–0.8 mm;

petals elliptic, 2.5–3.4 × 0.7–1.2 mm, adnate to androphore;

nectary glands ovate to subulate, 0.7–1 × 0.3–0.4 mm, free from androphore, glabrous;

stamens 10, staminodes 3–5, glabrous.

Pistillate flowers

sepals lanceolate to elliptic, 6–7 × 1.7–3.2 mm, without glands;

petals 0 or 5, linear, 0–1.7 mm;

nectary glands oblong, 0.5 × 0.7 mm, glabrous;

ovary tomentose to lanulose;

styles 1.5–3 mm, tomentose;

stigmas flattened.

sepals lanceolate, 3–6.5 × 0.7–1.8 mm, without glands;

petals 5, elliptic, 1.8–3 × 0.7–1.4 mm;

nectary glands oblate, elliptic to ovate, 0.4–1 × 0.5–0.7 mm, glabrous, rarely pubescent;

ovary strigose to hispidulous;

styles 1.5–2 mm, glabrous;

stigmas flattened.

Capsules

7–9 mm, tomentose to lanulose.

3–5 mm, strigose to hispidulous.

Seeds

3.7–5 mm, smooth, lightly tuberculate, or striate.

1.8–2.5 mm, foveolate, striate.

Argythamnia aphoroides

Argythamnia lanceolata

Phenology Flowering Jan–Jul. Flowering year-round.
Habitat Bluestem-grama grasslands, oak woodlands, calcareous, often rocky, clay or loam soils. Desert scrub, rocky soils.
Elevation 300–600 m. (1000–2000 ft.) 0–1000 m. (0–3300 ft.)
Distribution
from FNA
TX
[BONAP county map]
from FNA
AZ; CA; Mexico (Baja California, Baja California Sur, Sonora)
[WildflowerSearch map]
[BONAP county map]
Discussion

Argythamnia aphoroides is restricted to the Edwards Plateau.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Argythamnia lanceolata is a common shrub of the Sonoran Desert and is easily recognized by its densely strigose, lanceolate to ovate, usually entire leaves, strongly flattened stigmas, and staminate flower petals adnate to the androphore. Plants from shady canyons tend to have broader and less hairy leaves.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 12, p. 174. FNA vol. 12, p. 177.
Parent taxa Euphorbiaceae > Argythamnia Euphorbiaceae > Argythamnia
Sibling taxa
A. adenophora, A. argothamnoides, A. argyraea, A. brandegeei, A. claryana, A. cyanophylla, A. humilis, A. lanceolata, A. mercurialina, A. serrata, A. simulans
A. adenophora, A. aphoroides, A. argothamnoides, A. argyraea, A. brandegeei, A. claryana, A. cyanophylla, A. humilis, A. mercurialina, A. serrata, A. simulans
Synonyms Ditaxis aphoroides Serophyton lanceolatum, Aphora lanceolata, A. palmeri, A. sericophylla, A. sericophylla var. verrucosemina, Ditaxis lanceolata, D. palmeri, D. sericophylla
Name authority Müller Arg.: Linnaea 34: 146. (1865) — (as Argyrothamnia) (Bentham) Müller Arg.: Linnaea 34: 148. (1865) — (as Argyrothamnia)
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