Perennials, 10–80 cm. Stems erect, branched from bases or throughout. Leaves basal and cauline; proximal opposite (sometimes rosettes), distal alternate; ± sessile; blades oblong to linear, lance-linear, or oblanceolate, margins entire or toothed, faces hirsute to strigose or pubescent and (distal leaves) stipitate-glandular. Heads radiate or discoid, borne singly or in corymbiform or racemiform arrays. Peduncular bracts: pit-glands, tack-glands, and/or spines 0 at tips. Involucres ± globose or broadly ellipsoid to campanulate, 4–6+ mm diam. Phyllaries 0 (see paleae at receptacles) or falling, 1–3 or 7–15 in 1 series (lanceolate to lance-attenuate or oblanceolate, herbaceous, each 1/2 or fully enveloping subtended ray floret proximally, ciliolate, abaxially stipitate-glandular, sometimes hirtellous). Receptacles flat to convex, glabrous or setulose, paleate (paleae falling, in 1 series, between rays and discs, usually connate, sometimes distinct, phyllary-like, more scarious; in discoid heads, functionally an “involucre”). Ray florets 0, 1–3, or 8–15, pistillate, fertile; corollas yellow. Disc florets 5–30, bisexual and fertile, or functionally staminate; corollas yellow, tubes shorter than funnelform throats, lobes 5, deltate (styles glabrous proximal to branches; anthers yellow). Ray cypselae (black or grayish) compressed or ± obcompressed, clavate, ± arcuate (basal attachments centered, apices beaked, beaks offset adaxially, 0.2–0.3 mm, faces glabrous or hairy); pappi 0 or coroniform. Disc cypselae (black or grayish) ± terete, clavate (± straight, faces hairy); pappi of 5–8 or 11–21 lanceolate, linear, quadrate, or subulate, ciliolate-plumose, erose, or fimbrillate scales. x = 7.
w North America.
Species 2 (2 in the flora).
Following B. G. Baldwin (1999b), Anisocarpus comprises two species that have resided in different genera and different tribes. Anisocarpus scabridus was placed in Raillardella or Raillardiopsis—both regarded as members of Senecioneae until S. Carlquist’s (1959) anatomic studies. Anisocarpus madioides was treated in Madia and included in D. D. Keck’s (1959) informal “section Anisocarpus,” along with the other pappose species of Madia in the sense of Keck (now treated in Harmonia, Jensia, and Kyhosia). Molecular phylogenetic data support a sister-group relationship between A. madioides and A. scabridus (Baldwin 1996).
Anisocarpus madioides and A. scabridus are the only perennial herbaceous tarweeds that combine non-scapiform capitulescences, radiate heads (at least in part), ellipsoid or spheric involucres, and yellow anthers, and are the only perennials in Madiinae with 2n = 14. The two species are highly distinct ecologically: A. madioides occurs in low- to mid-elevation, forest and woodland understories; A. scabridus occurs on high-elevation, exposed scree slopes and ridges.
Artificial hybrids between the two species are vigorous, easily produced (with Anisocarpus madioides as seed parent), and largely pollen-sterile, except for large, diploid grains. B. G. Baldwin used diploid pollen from an F1 hybrid between A. madioides and A. scabridus in an artificial hybridization with a member of the closely-related Hawaiian silversword alliance, Dubautia knudsenii Hillebrand, a wet-forest tree from Kaua‘i (see M. Barrier et al. 1999).
|1||Leaves dark green, 40–130 mm, margins entire or toothed, apices acute; involucres ± globose, 4–6 mm; ray florets 8–15; disc florets functionally staminate; cypselae compressed; disc pappi of 5–8 linear, lanceolate, or quadrate, fimbrillate or erose scales 0.2–1.5 mm||Anisocarpus madioides|
|1||Leaves blue-green to grayish blue-green, 10–30 mm, margins entire, apices acute or obtuse; involucres broadly ellipsoid to campanulate, 6–12 mm; ray florets 0 or 1–3; disc florets bisexual, fertile; ray cypselae ± compressed; disc pappi of 11–21 subulate, ciliate-plumose scales 4–7 mm||Anisocarpus scabridus|