Habit and leaf form. Herbs (forming small, loose groups; not requiring fire to induce flowering); deciduous. Perennial. Leaves basal. Tuberous (tubers large, obovoid). Helophytic, or mesophytic. Leaves medium-sized to very large; leathery; petiolate; simple. Leaf blades entire; flat (margins sometimes incurved); linear to ovate (narrow); parallel-veined; cross-venulate, or without cross-venules. Leaf blade margins entire. Vernation conduplicate. Leaf anatomy. Hairs absent. Stem anatomy. Secondary thickening absent.
Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Entomophilous. Pollination mechanism conspicuously specialized.
Inflorescence and flower features. Flowers aggregated in ‘inflorescences’. Inflorescence few-flowered (to 10-flowered). Flowers in racemes. The terminal inflorescence unit racemose. Inflorescences scapiflorous, or not scapiflorous; terminal; stem bracts present. Flowers medium-sized to large; fragrant; very irregular; zygomorphic; resupinate. The floral asymmetry involving the perianth and involving the androecium. Flowers 3 merous; cyclic; supposedly basically pentacyclic. Perigone tube absent. Perianth of ‘tepals’, or with distinct calyx and corolla; 6; 2 -whorled; isomerous (but zygomorphic); free; dull-coloured, green, red, and brown. Calyx (if the outer whorl be so designated) 3 (the median member ostensibly posterior); 1 -whorled; polysepalous. Corolla (i.e. the members of the inner whorl) 3; polypetalous; imbricate. Androecium 3, or 1 (by misinterpretation). Androecial members free of the perianth; united with the gynoecium (fused with the style to form a column or ‘gynostemium’; column curved, apex with a point); coherent (via the gynostemium); 1 - adelphous; theoretically 2 -whorled. Androecium including staminodes, or exclusively of fertile stamens (by misinterpretation). Staminodes 2 (these anterior (ostensibly posterior), supposedly the abaxial pair of the inner whorl). Stamens 1 (this across the flower from the labellum, i.e. anterior but ostensibly posterior, supposedly representing the outer whorl); reduced in number relative to the adjacent perianth; alterniperianthial (i.e. with reference to the single stamen, across the flower from the labellum); filantherous, or with sessile anthers. Anthers dorsifixed to basifixed; dehiscing via longitudinal slits; introrse; tetrasporangiate; appendaged, or unappendaged. Pollen shed in aggregates; in the form of pollinia. Gynoecium 3 carpelled. The pistil 1 celled. Carpels isomerous with the perianth. Gynoecium syncarpous; eu-syncarpous; inferior. Ovary unilocular; 1 locular. The ‘odd’ carpel anterior (away from the labellum). Gynoecium stylate. Styles 1 (inflexed); apical. Stigmas 1; 3 - lobed (but becoming much modified in form, the apex of the median lobe forming the ‘rostellum’); wet type; papillate; Group III type. Placentation parietal. Ovules not differentiated; in the single cavity 30–100 (i.e. very numerous); non-arillate; anatropous.
Fruit and seed features. Fruit non-fleshy; dehiscent; a capsule. Capsules septicidal, or loculicidal. Fruit 30–500 seeded (i.e. seeds usually very numerous). Seeds endospermic (endosperm development arrested very early), or non-endospermic; minute; without starch. Embryo rudimentary at the time of seed release, or weakly differentiated. Seedling. Seedling collar not conspicuous. Primary root ephemeral.
Geography, cytology, number of species. Native of Australia. Endemic to Australia. Australian states and territories: Western Australia, Queensland, New South Wales, Victoria, Australian Capital Territory, and Tasmania. South-West Botanical Province.
Additional comments. The flowers produce a distinct rattle when shaken, hence the common name of ‘rattle beaks’.
Additional characters Perianth of 5 similar members and the median inner member modified into the labellum, or of 5 dissimilar members and the median inner member modified into the labellum (adaxial sepal hooded over the column, broad; lateral sepals and petals narrower, spreading; labellum curved, shorter than the sepals, with 2 shallow column-embracing lobes). Leaves solitary. Leaves erect. Perianth not glossy. Labellum with calli (calli of L. serratus dense, fleshy, cylindrical, giving a brush-like appearance to the labellum).