Rhadinothamnus Paul G.Wilson
Nuytsia 1(4):197 (1971)

Name Status: Current
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Scientific Description
H.R. Coleman, Friday 3 October 2008

Family Rutaceae.

Habit and leaf form. Silvery shrubs; evergreen, or deciduous; bearing essential oils. Mesophytic, or xerophytic. Leaves alternate; leathery, or ‘herbaceous’; petiolate; non-sheathing; gland-dotted; aromatic; simple, or compound; when compound ternate, or pinnate, or bipinnate, or unifoliolate. Leaf blades when simple dissected, or entire; when simple/dissected pinnatifid, or much-divided; pinnately veined, or one-veined. Leaves without stipules, or with stipules. Stipules when present, intrapetiolar; represented by glands. Leaves without a persistent basal meristem. Leaf anatomy. Hairs absent (lepidote trichomes present). Stem anatomy. Nodes unilacunar, or tri-lacunar. Secondary thickening developing from a conventional cambial ring.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Entomophilous.

Inflorescence and flower features. Flowers solitary, or aggregated in ‘inflorescences’; axillary; in cymes. The terminal inflorescence unit cymose, or racemose. Inflorescences terminal, or axillary, or epiphyllous. Flowers bracteate; pedicel bi- bracteolate (in lower half); small to medium-sized; fragrant; regular, or somewhat irregular. The floral asymmetry when noticeable, involving the perianth and involving the androecium (not K). Flowers (3–)5 merous; cyclic. Floral receptacle developing a gynophore (associated with the disk), or with neither androphore nor gynophore. Free hypanthium absent. Hypogynous disk present (short); intrastaminal; annular (sometimes one-sided), or of separate members. Perianth with distinct calyx and corolla; (3–)6, or (6–)10; 2 -whorled; isomerous. Calyx present; (3–)4, or 5; 1 -whorled; gamosepalous; undulately lobed; imbricate; patelliform or hemispherical; regular; with the median member posterior. Corolla (3–)4, or 5; 1 -whorled; polypetalous, or gamopetalous; valvate; regular, or unequal but not bilabiate; white. Androecium 2, or 3, or 5, or 8, or 10, or 20–60. Androecial members unbranched, or branched (? by the splitting of simple primordia); free of the perianth; all equal, or markedly unequal; free of one another, or coherent (? the filaments usually more or less basally connate); 1 - adelphous, or 3–12 - adelphous; 1 -whorled, or 2 -whorled. Androecium exclusively of fertile stamens, or including staminodes. Staminodes (often representing the antepetalous whorl) (3–)4, or 5(–10). Stamens 2–60; reduced in number relative to the adjacent perianth to polystemonous; alternisepalous, or oppositisepalous (? when the outer whorl lost). Anthers dorsifixed, or basifixed (? more or less); versatile; dehiscing via longitudinal slits; introrse, or latrorse; tetrasporangiate; appendaged; apiculate (apiculum non-glandular). Gynoecium (1–)3 carpelled, or 4–5(–100) carpelled. The pistil when syncarpous, (1–)4–5(–100) celled. Gynoecium apocarpous, or syncarpous; eu-apocarpous, or semicarpous, or synstylous; superior. Carpel with or without a sterile apex; (when apo- or semicarpous) (1–)2–100 ovuled. Placentation of the free carpels marginal. Ovary unilocular, or plurilocular; when syncarpous, (1–)4–5(–100) locular. Styles 1, or 3–5; free, or partially joined; apical. Stigmas wet type, or dry type; papillate, or non-papillate; Group II type, or Group IV type. Placentation when syncarpous, axile. Ovules 1–5(–50) per locule; pendulous to ascending; epitropous; when two or more per cell, collateral, or superposed, or biseriate; arillate, or non-arillate; anatropous, or hemianatropous.

Fruit and seed features. Fruit fleshy, or non-fleshy; an aggregate, or not an aggregate. The fruiting carpel dehiscent, or indehiscent; baccate (cocci erect). Fruit (when syncarpous) dehiscent, or indehiscent, or a schizocarp. Mericarps when schizocarpic, comprising berrylets, or comprising follicles, or comprising nutlets, or comprising drupelets. Fruit when syncarpous and non-schizocarpic, a berry, or a drupe. Seeds narrow-reniform or bluntly ellipsoidal; endospermic, or non-endospermic. Embryo well differentiated. Cotyledons 2. Embryo chlorophyllous, or achlorophyllous; straight, or curved, or bent. Seedling. Germination phanerocotylar, or cryptocotylar.

Physiology, biochemistry. Aluminium accumulation not found. Photosynthetic pathway: C3.

Geography, cytology, number of species. A genus of 4 species.

Additional characters Petals shortly uninerved, or multinerved.

Taxonomic Literature

Wheeler, Judy; Marchant, Neville; Lewington, Margaret; Graham, Lorraine (2002). Flora of the south west, Bunbury, Augusta, Denmark. Volume 2, dicotyledons. Australian Biological Resources Study. Canberra.

Grieve, B. J.; Blackall, W. E. (1998). How to know Western Australian wildflowers : a key to the flora of the extratropical regions of Western Australia. Part II, Dicotyledons (Amaranthaceae to Lythraceae). University of W.A. Press. Nedlands, W.A.

Wilson, Paul G. (1998). New species and nomenclatural changes in Phebalium and related genera (Rutaceae) [electronic resource].