187m.5. Asteraceae Martinov (tribe Heliantheae) subtribe Guardiolinae H. Robinson, Phytologia. 41: 41. 1978.
Perennials or subshrubs, (10–)30–100[–200] cm. Leaves cauline; opposite; ± petiolate; blades deltate or rounded-deltate to ovate [lanceolate to linear] (bases often hastate), margins usually dentate, faces glabrous or glabrate. Heads radiate, in corymbiform arrays [borne singly]. Calyculi 0. Involucres narrowly cylindric [campanulate]. Phyllaries persistent, 3–5 in 1 series (distinct, oblong or lanceolate to linear, subequal, herbaceous, conduplicate, streaked with 8–12+ translucent nerves, margins often membranous). Receptacles convex, paleate (paleae similar to phyllaries, membranous, conduplicate, each enfolding a floret). Ray florets 1–5, pistillate, fertile; corollas whitish (tubes often longer than laminae). Disc florets 3–20+, functionally staminate; corollas whitish, tubes longer than abruptly dilated, campanulate to funnelform throats, lobes 5, lanceolate to lance-linear; anther thecae green (filaments hairy); stigmatic papillae 0 or vestigial. Cypselae ± ellipsoid [fusiform to clavate], ± obcompressed, smooth or fine-ribbed, glabrous (bases carunculate); pappi 0 [5–6, erose scales].
Genus 1, species 10 (1 species in the flora): w United States, Mexico.
Guardiola has been included in Melampodiinae (G. Bentham 1873) and in Coreopsidinae (T. F. Stuessy 1973). According to H. Robinson (1981), the "glands on the anther appendages" in Guardiola "are distinct and massive, unlike...other Heliantheae."