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false rosinweed, osmadenia

osmadenia

Habit Annuals, 5–40 cm (self-incompatible; herbage strongly scented).
Stems

erect (branched, branchlets relatively many, commonly spreading, threadlike, densely glandular, scabrous to shaggy-hairy).

Leaves

(proximal) 1–3(–5) cm, smaller distally.

mostly cauline; alternate;

sessile;

blades linear, margins entire, faces hispidulous and glandular (proximally ± ciliate or shaggy-hairy).

Involucres

ovoid, 2–4 mm diam.

Receptacles

flat, glabrous, paleate (paleae persistent, in 1 series between rays and discs, connate, forming cups, distinct apices acute, often apiculate).

Ray florets/Ray corollas

tubes ca. 2.5 mm, laminae ca. 4 mm.

3–5, pistillate, fertile;

corollas wholly or mostly white (laminae 3-lobed, lobes sometimes each with prominent medial red blotch, overall often fading reddish, sinuses ± equaling laminae).

Disc florets/Disc corollas

3–5 mm, lobes ± hirsute.

3–10, bisexual, fertile;

corollas usually wholly white, sometimes lobes each with prominent medial red blotch or reddish overall, tubes shorter than throats, lobes 5, deltate (anthers ± dark purple; styles glabrous proximal to branches).

Phyllaries

3.5–6.5 mm (paleae 4–6 mm) ± strigillose, strongly glandular, abaxial faces bristly, shaggy-hairy, especially margins and apices.

falling, 3–5 in 1 series (each partly enveloping a ray cypsela, apices acute to attenuate).

Heads

radiate, in loose, cymiform arrays.

Cypselae

(rays) 1.8–2.7 mm, beaks 0.3 mm, or (discs) 2–2.5 mm;

pappi of scales 4–6 mm plus scales ca. 1 mm.

(rays) ± obcompressed (± 3-angled, abaxial sides usually broadly 2-faced, angles between those faces usually 90+°, adaxial sides nearly flat), apices beaked, beaks off center, faces rugose, glabrous;

or (discs) narrowly clavate, appressed-hairy;

pappi (rays) 0, or (discs) of 4–5 lance-attenuate to aristate scales alternating with 4–5 shorter, ± fimbriate scales.

Peduncular

bracts 4–7, narrowly lanceolate, 4–8 mm.

bracts with tack-glands 0 (strigillose, strongly glandular, margins often proximally pectinate, ciliate).

x

= 9.

2n

= 18.

Osmadenia tenella

Osmadenia

Phenology Flowering spring–summer.
Habitat Barren, often rocky, exposed hillsides, canyons, chaparral, woodlands
Elevation 10–600(–1200) m (0–2000(–3900) ft)
Distribution
from FNA
CA; Mexico (Baja California)
[WildflowerSearch map]
[BONAP county map]
from FNA
CA; nw Mexico
[BONAP county map]
Discussion

Species 1.

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

Source FNA vol. 21, p. 269. FNA vol. 21, p. 269. Authors: Robert L. Carr, Gerald D. Carr.
Parent taxa Asteraceae > tribe Heliantheae > subtribe Madiinae > Osmadenia Asteraceae > tribe Heliantheae > subtribe Madiinae
Subordinate taxa
O. tenella
Synonyms Calycadenia tenella
Name authority Nuttall: Trans. Amer. Philos. Soc., n. s. 7: 392. (1841) Nuttall: Trans. Amer. Philos. Soc., n. s. 7: 391. (1841)
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