Oedera Linneaus (1771: 159)

Bergh, Nicola G., Bentley, Joanne & Verboom, George Anthony, 2018, Classification of the Relhania generic group (Asteraceae, Gnaphalieae) revisited using molecular phylogenetic analysis, Phytotaxa 344 (2), pp. 101-132 : 116-117

Oedera Linneaus (1771: 159) , nom. cons. Eroeda Levyns [1948: 83] , nom. illeg.

Type species: Oedera capensis (Linnaeus f.) Druce.

Diagnostic features: Oedera as broadly circumscribed here is characterised by morphological heterogeneity in most characters, but all species are woody subshrubs with heterogamous, radiate capitula, the ray laminas being yellow, in some species with purple-brown stripes abaxially. The genus is distinguished from the only other southern African members of the Gnaphalieae to have yellow ray laminas, Arrowsmithia and Macowania , by leaves that are not revolute and not densely white-woolly abaxially. Also, most Macowania species have a thickened and glabrous leaf abaxial midrib coupled with a canaliculate adaxial surface, which is never present in Oedera . The genera of the “short-lived clade”, viz. Leysera , Nestlera and Rhynchopsidium also have yellow rays, but are distinguished from Oedera by having the annual or biennial life-history. The one perennial species of Leysera ( L. gnaphalodes ) is distinguished from Oedera species by the possession of plumose pappus bristles; where species of Oedera posssess pappus bristles, these are always scabrid or barbellate.

Description:

Habit: well- or sparsely branched woody shrublets or subshrubs, occasionally resprouting from an underground rootstock, sometimes spinescent, leaves crowded at the branch tips, older stems often with old leaf-scars or occasionally clothed with old leaf-bases; stems, leaves and peduncles glabrous or tomentose to varying degrees, often glandular. Leaves alternate or occasionally opposite-decussate, sometimes fasciculate, sessile, occasionally semi-amplexicaul, entire, occasionally with tooth-like marginal trichomes; linear to linear-lanceolate to oblanceolate to almost orbicular, occasionally terete and fleshy, apically acuminate to obtuse, often apiculate; usually with distinct midrib, sometimes with multiple (up to nine) parallel veins; flat or adaxially concave, margins flat or involute, when involute then the concave leaf adaxial surface usually filled with a dense bright white tomentum; with sparse to dense covering of glandular as well as eglandular trichomes; glandular trichomes multicellular, sessile or stalked; if sessile then borne at the level of the epidermis or embedded in pits; leaf surface sometimes resiniferous. Capitula terminal, sessile or on short to elongate peduncles, radiate; solitary, paired or clustered in umbel-like cymes, or occasionally the cluster forming a compound secondary head (syncephalium) modified to look like a single radiate capitulum and subtended by a pseudo-involucre of leaves; vegetative growth proceeding from below the previous year’s synflorescence. Involucre urceolate, cyathiform and campanulate to obconical, bracts tightly imbricate in several series, becoming progressively longer inwards, yellowish brown, with a thickened stereome and scarious lamina, apically acute to obtuse, innermost often obovate to spathulate, lamina spreading or erect, sometimes lamina and margins translucent and/or whitish, abaxially glabrous, tomentose or sparsely glandular. Receptacle flat or conical (deeply alveolate in Oe. garnotii ), paleate or epaleate, paleae persistent or deciduous; sometimes also shortly squamose. Ray florets female-fertile, tube yellow, cylindrical or funnel-shaped or triquetrous, glabrous or sometimes with scattered, subulate-triangular hairs, often with stalked trichomes, rarely tubular, usually with a long spreading lamina, lamina elliptic or elliptic-oblong to lorate, yellow, occasionally with a brownish-purple stripe abaxially; apically minutely three-lobed; style terete, bifid, branches radially oriented, apically obtuse to acute, glabrous or seldom minutely penicillate apically, with stigmatic surfaces basally separated but apically confluent; cypselas as in disc florets, but more densely hairy, sometimes with a basal hair tuft; pappus of short scales fused to varying degrees, rarely with a few additional nude or barbellate bristles, occasionally the pappus comprising barbellate bristles only. Disc florets usually perfect, structurally hermaphrodite but female-sterile in a few species (Oe. garnotii, Oe. epaleacea, Oe. relhanioides, Oe. spathulifolia, Oe. tricephala and possibly Oe. longipes ; sometimes in Oe. acerosa ); corolla deep yellow, ± distinctly divided into a cylindrical tube and cyathiform or funnel–shaped limb; tube glabrous or with a sparse to dense covering of multicellular glandular trichomes; limb five-lobed, lobes spreading, ovate-triangular, marginally thickened with well-developed veins and with multicellular glands abaxially; style terete, base bulbous and frequently attached to a short stylopodium; fertile style branches narrowly oblong, terminally penicillate, sometimes apically and dorsally minutely pilose-penicillate, obtuse to truncate, stigmatic bands separated, not meeting at the tips; sterile style apices simple or only shallowly cleft; cypselas flattened to angular to terete, elliptic-oblong to oblong to linear, elongate and slender, glabrous or laxly to densely pubescent; anthers linear, with a flat, ovate apical appendage and long to inconspicuous subulate tails, unbranched or very slightly branched; pappus a crown of many, subulate to triangular, short scarious scales fused to varying degrees, seldom also with a few nude or barbellate, apically flattened bristles.

Cytology: the only observed base number is x = 7; generally 2n = 14.