Monadenia Lindl.

Scientific Description

Family Orchidaceae.

Habit and leaf form. Herbs. Plants succulent (stem fleshy). Perennial; plants with a basal concentration of leaves (rosette loose), or with neither basal nor terminal concentrations of leaves (all cauline and gradually reduced upward); tuberous (tuber fleshy, ovoid). Helophytic, or mesophytic. Leaves medium-sized to large; alternate; spiral; ‘herbaceous’, or leathery, or fleshy; imbricate, or not imbricate; petiolate; simple. Leaf blades entire; rolled (channelled); ovate (narrow, tapered); 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. Pollinated by unusual means (apparently self-pollinating, every seed capsule swelling once flowering has finished). Pollination mechanism conspicuously specialized, or unspecialized.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’. Inflorescence many-flowered (usually). Flowers in spikes (dense). The terminal inflorescence unit racemose. Inflorescences scapiflorous, or not scapiflorous; terminal. Flowers prominently bracteate; small; fragrant, or odourless; 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 (although the adaxial sepal may overlap the petals to form a loose galea); green to white, or yellow (tipped). 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; not spurred, or spurred (by misinterpretation). 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 short); 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 (pollinia 2). 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. Adventive. Australian states and territories: Western Australia. South-West Botanical Province.

Additional characters Perianth of 5 dissimilar members and the median inner member modified into the labellum (adaxial sepal hood-shaped, almost always with a prominent, descending basal spur; lateral sepals spreading or deflexed, narrower than the adaxial sepal; lateral petals erect, entire or 2-lobed; labellum usually small and narrow, undivided). Leaves not solitary (usually numerous). Leaves erect. Labellum not insect-like. Perianth not glossy.