Tanacetum atkinsonii (Clarke) Kitamura

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

Erect herbs from fleshy root-stock.Leaves 2-4-pinnatisect,alternate.Capitula radiate,disciform or discoid,solitary or 2-4 in loose raceme.Involucre hemispherical;phyllaries imbricate,c 4-seriate,ovate to linear-oblong,with pale or dark scarious margins.Receptacle convex,naked.Marginal flowers ligulate,female,or tubular-campanulate with some female or ± bisexual with reduced androecium and others undifferentiated from disc flowers.Disc flowers bisexual;corollas tubular-campanulate,5-toothed;style branch tips truncate,hairy. Achenes oblong or clavate, terete, 5-10-ribbed; myxogenic cells absent. Pappus absent or reduced to c 3 minute teeth in our species.

Species description

Root-stock thick,fleshy;stems erect,usually simple,15-42cm,puberulous,lanate beneath capitulum.Basal leaves 3(-4)-pinnatisect,obovate in outline,12-30cm,sparsely pubescent with long fine hairs,ultimate segments narrowly oblong,acuminate,c 0.5mm wide. Cauline leaves reduced,mostly 2-pinnatisect.Capitula usually solitary,terminal,rarely 1-3 more on short lateral branches,radiate.Involucre hemispherical,c 1.5cm diameter;phyllaries oblong-lanceolate,6-10 x 1.5-3mm,obtuse,scarious margin blackish,eroded. Flowers often sparsely glandular below;corollas yellow.Ray flowers 15-25;ligules 12-17 x 3-5mm,densely papillose inside,staminodes exerted.Disc corollas 3-4.5mm.Achenes c 2.5mm,5-ribbed,minutely glandular;pappus usually absent,sometimes achene rim developed into 3 small lobes.