Disa bracteata, South African Weed Orchid

Image/s
Category
Lilies and bulbs
Scientific Name
Disa bracteata
Common Name/s
South African Weed Orchid
Weed Information

Threat: High threat environmental weed

Description: A robust, erect, fleshy perennial orchid 30–50cm high with annual above-ground growth from tubers. One plant grows up to 60 tiny flowers in a dense spike. It has a self-pollinating reproductive strategy and produces millions of dust-like seeds. It is the only invasive, non-native orchid in Victoria.

Flowers: Small with hooded red-brown upper parts and yellow-green thin, downward pointing lower parts. Borne on a thick cylindrical spike 5–20cm long. Each flower is surrounded by a conspicuous tapering modified leaf.

Fruits: Brown capsule containing minute dust-like seeds. Seed set and dispersal occurs at the end of November.

Leaves: Leaves numerous with parallel veins, decreasing in size progressively up the stem; lower leaves 5–15cm long. Leaves initially form a clump at the base, and then numerous grass-like leaves with purplish under-surfaces develop on the lower stem as it lengthens. Modified leaves also embrace each flower.

Note: Seeds readily spread by wind, on vehicles, and via clothing, shoes and camping equipment. Self-pollinating, forming dense colonies that may replace native ground flora. Populations of this orchid have increased rapidly where the species has established.

Similar indigenous species: Similar to Onion-orchids (Microtis spp.) and Leek-orchids (Prasophyllum spp.). However, these orchids have single leaves which are not purple underneath.

Control measures: Slashing, mowing and hand removal.

Dispersal: Vegetative, wind.