Winter greenhood (Pterostylis alobula)
Description
Pterostylis alobula, commonly known as the winter greenhood, is a species of orchid endemic to New Zealand. As with similar greenhoods, the flowering plants differ from those which are not flowering. The non-flowering plants have a rosette of leaves flat on the ground but the flowering plants have a single flower with leaves on the flowering spike. This greenhood has pale green and white-striped flowers, similar to those of another New Zealand greenhood, P. trullifolia but are larger and paler in colour. Pterostylis alobula is a terrestrial, perennial, deciduous, herb with an underground tuber and when not flowering, a rosette of mostly egg-shaped leaves, 5–15 millimetres (0.2–0.6 in) long and 4–15 millimetres (0.2–0.6 in) long with a stalk up to 10 millimetres (0.4 in) long. Flowering plants usually have a single pale green flower with white stripes 10–20 millimetres (0.4–0.8 in) high borne on a flowering stem up to 150 millimetres (6 in) high with between two and six linear to lance-shaped stem leaves 5–25 millimetres (0.2–1 in) long and 3–6 millimetres (0.1–0.2 in) wide. The dorsal sepal and petals are fused, forming a hood or "galea" over the column with its tip usually horizontal. The lateral sepals are erect, held closely against the galea and have a broad V-shaped sinus between their bases. The labellum is red, curved and projects above the sinus. Flowering occurs from March to October.
Taxonomic tree
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Domain: Eukarya
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Kingdom: Plantae
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Phylum:
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Class: Liliopsida
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Order: Asparagales
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Family: Orchidaceae
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Genus: Pterostylis
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