Petasites tricholobus Franch.

Family Description

Annual, biennial or perennial herbs, sometimes shrubs, rarely trees, tissues sometimes containing milky sap, glabrous, pubescent, tomentose, spinous or variously sessile- or stipitate-glandular. Leaves alternate or sometimes opposite, exstipulate (but sometimes with stipuliform appendages), entire, toothed, lobed or variously dissected. Individual flowers usually numerous, aggregated and ± sessile (briefly immersed to very shortly stipitate) on a common receptacle and surrunded by an involucre of 1-many series of phyllaries (involucral bracts),the whole comprising a capitulum; phyllaries free, rarely connate; capitula solitary to very many, rarely agreegrated into secondary capitulum-like glomerules.Receptable sometimes bearing paleae (scales), hairs or bristles.Flowers (florets)epigynous, bisexual, female, m ale(at least functionally so) or neuter (sterile). Calyx absent, often replaced on apex of ovary by a pappus of 1 or more series of bristles and / orscales. Corolla gamopetalous, tabular throughout or dilated or 1(-2)-lipped above,variously truncate or 1-5-toothed at apex (appices); rarely corolla absent. Stamens (1-)5, epipetalous, filaments free anthers laterally connate into a cylinder around style (free in one species). Ovary inferior, 1-celled with one basal ovule; style usually divided above into two branches, sometimes entire on male flowers, emerging through anther cylinder, first collecting and exposing pollen,later exposing stigmatic surfaces if bisexual. Fruit an achene (cypsela) usually bearing a persistent or deciduous pappus; pappus sessile or borne on a beak(rostrum).

Genus Description

Subdioecious rhizomatous perennial herbs. Basal leaves renifrom, petiolate. Inflorescence scapose, ± paniculate, rachis bearing scale leaves; capitula disciform or discoid. Involucre campanulate, calyculate; phullaries 1-seriate, equal. Receptacles flat, naked. Female flowers filiform; corolla slightly broadened above with (3-)4(-5) unequal, narrow teeth in our species. Disc flowers tubular-campanulate, male; corolla ± equally 5-toothed at apex; style thickened above, abruptly 5-10 ribbed; pappus bristle numerous, scarbid.

Species description

Basal leaves scarcely developed at flowering, when lamina 5-10 x 5-10cm, acute or obtuse, base deeply cordate, margins denticulate, ± glabrous above, white araneous beneath at first, petioles 5-30cm. Scapes 10-30cm, inflorescence corybose at first, with 6-20capitula; basal scale leaves ovate or oblong, 2-3 x 1-1.5cm, acute, basal sessile. Involure 5-7m diameter, sparsely araneous at base; phyllaries c 15, lanceolate, 10 x 2mm, purplish. Flowers white or purplish. Female corollas 10mm (female capitula usually with few male flowers near centre). Male corollas 8-10mm (male capitula usually without female flowers-none seen from our area). Achnes oblong, 3.5mm; pappus white, 10mm.