The flower of Dietes grandiflora is a rhizomatous perennial growing a tuft of long, fibrous, sword-shaped leaves arranged in the shape of a fan. Dietes refers to the plant’s dual resemblance links to both the genera of Iris and Moraea.

The flower is characterised by prominent dark yellow nectar guides on the three bigger (inner) tepals. The other (outer) three are white with two thin parallel brown lines at the base. These plants flower well, justifying the grandiflora name for its big (10 cm in diameter) flowers on erect stems of a metre tall, often blooming after summer rain. The style is prominently branched into flattened blue or violet petal-like sections protruding above the tepals and hiding the anthers.

The flowers last for only two or three days, rendering them just about unsuitable as cut flowers. The oblong green seed capsules eventually split open to release small dark seeds. 

The plant is found in coastal parts of the Eastern Cape and KwaZulu-Natal among evergreen scrub. It is not considered to be threatened in its habitat early in the twenty first century (Manning, 2009; http://redlist.sanbi.org).