Otion

Scientific Description

Family Papilionaceae. Mirbelieae.

Sometimes included in Aotus phylicoides, Burtonia simplicifolia, Oxylobium microphyllum, Phyllota luehmannii. Sometimes included in Leguminosae.

Habit and leaf form. Shrubs. Plants unarmed. Self supporting. Leaves alternate; spiral; simple; epulvinate. Leaf blades dorsiventral; rolled; without cross-venules. Leaves without stipules. Leaf blade margins not prickly; revolute. Leaf anatomy. Complex hairs present, or absent (? — peltate hairs present or absent).

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

Inflorescence and flower features. Flowers solitary (Oxylobium microphyllum), or aggregated in ‘inflorescences’ (Aotus phylicoides); not crowded at the stem bases; when solitary, axillary; when aggregated, in racemes (short, dense). Inflorescences simple. The terminal inflorescence unit racemose. Inflorescences terminal. Flowers pedicellate; (bi-) bracteolate. Bracteoles persistent. Bracteoles adnate to the calyx, cf. Pultenaea. Flowers small; very irregular; zygomorphic. The floral asymmetry involving the perianth, or involving the perianth and involving the androecium. Flowers papilionaceous; tetracyclic. Floral receptacle developing a gynophore. Free hypanthium present, or absent. Perianth with distinct calyx and corolla; 10; 2 -whorled; isomerous. Calyx present; 5; 1 -whorled; gamosepalous; (five) lobed. Calyx lobes markedly shorter than the tube to about the same length as the tube. Calyx imbricate; exceeded by the corolla; bilabiate; non-fleshy; persistent; non-accrescent; with the median member anterior. Epicalyx present (representing the adnate bracteoles). Corolla present; 5; 1 -whorled; appendiculate, or not appendiculate. Standard not appendaged. Corolla polypetalous, or partially gamopetalous. 2 of the petals joined. The joined petals anterior (the keel pair). The wings of the corolla free from the keel; laterally spurred. Standard ‘normally’ developed; emarginate; not sericeous. Keel about equalling the wings, or conspicuously exceeding the wings; not long-acuminate/beaked; neither coiled nor spiralled; not bent and beaked. Corolla imbricate; not fleshy; deciduous; non-accrescent. Petals clawed. Androecial members definite in number. Androecium 10. Androecial sequence determinable, or not determinable. Androecial members free of the perianth; all equal, or markedly unequal; free of one another; 1 -whorled. Androecium exclusively of fertile stamens. Stamens 10; all more or less similar in shape; diplostemonous; both opposite and alternating with the corolla members; filantherous. Anthers all alike; dehiscing via longitudinal slits; latrorse, or introrse. Gynoecium 1 carpelled. The pistil 1 celled. Carpels reduced in number relative to the perianth. Gynoecium monomerous; of one carpel; superior. Carpel stylate. Style curved. Style terete. Style glabrous. Stigmatic tissue terminal. Carpel 2–20 ovuled. Placentation marginal. Ovary subsessile to stipitate. Stigmas capitate, or punctiform.

Fruit and seed features. Fruit stipitate. Pods globose, or somewhat elongated; internally hairy. Fruit 1 celled. Seeds not mucous; minutely arillate, or non-arillate. Embryo bent (radicle inflexed). Testa non-operculate; conspicuously colour-patterned (mottled).

Geography, cytology, number of species. A genus of 6 species; 6 species in Western Australia (only one in December 1997 list).

Additional comments. Morphological details for Oxylobium microphyllum and Aotus phylicoides only. Note that in Crisp and Weston (1995), ‘bracteoles absent’ encoded in Table 2 is contradicted by their Fig 7 — where Pultenaea-type adnate bracteoles are clearly depicted in O. microphyllum, and even referred to in the legend.