Tuberous terrestrial orchids growing as scattered individuals, in crowded tufts, or in clonal colonies. Leaves 1 to a few, basal, sessile, distichous or spirally arranged, much longer than wide, often grass-like, prostrate or erect, channelled or not, straight or spirally twisted. Racemes 1-to many-flowered, short to tall; peduncle wiry, glabrous, with 1–3 sterile bracts. Flowers resupinate, large, colourful. Tepals free, markedly dissimilar. Dorsal sepal shorter and broader than lateral sepals, base hooding the column. Lateral sepals deflexed or recurved, long, narrow, often widest near apex, acute, parallel or crossed. Petals with narrow basal stalk and broad blade that are usually distinct from each other, but sometimes stalk widening into blade. Labellum attached by its base to column base. Labellum lamina 3-lobed from near base; lateral lobes flanking column, large or small; margins entire or erose/lobed, sometimes papillate; midlobe protruding forwards like a platform, flat or centrally ridged with downcurved margins, sometimes papillate. Callus of 1 or 2 ridges on labellum base, smooth or papillate, sometimes breaking up into accessory ridges on midlobe. Column short, stamen and style fused only at base; wings large, prominent. Anther with 2 bilobed white pollinia attached directly to viscidium.
These orchids grow mostly in open habitats such as forests, woodlands, grasslands, and on rocky outcrops, particularly granite. They range from coastal lowlands to montane and subalpine regions up to 1,800 m altitude. Soils where they grow are freely draining for the most part, but may be seasonally moist to wet in winter and spring. Some species from W.A. actually flower with the stem bases and the leaves submerged in water. Species of Diuris can be locally common in suitable habitats and create attractive floral displays.
Home