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The following article was written
for the Orchid Species Bulletin published by the Orchid
Species Society, which is based in Brisbane,
Queensland in May 2009.
Bear in mind that any cultivation notes refer to the sub-tropical conditions of Southern Queensland, Australia.
Vitekorchis excavata
(Lindl.) Ramowicz & Szlach. was first described by
John Lindley as Oncidium
excavatum Lindl. in Sertum
Orchidacearum in 1838, based on a specimen collected by A. Mathews in
northern Peru. Lindley gave it the specific epithet from the Latin excavatus
(excavated) due to the depression at the base of the underside of the lip.
Agnieszka Ramowicz and Dariusz Szlachetko transferred this species to Vitekorchis in the Polish
Botanical Journal in 2006.
DNA analyses show that several closely
related species that have been published in Vitekorchis
make up an isolated group without close relatives. The fifth and final volume of
Genera Orchidacearum, which is
scheduled to be published later this year, will accept this genus.
Vtk.
excavata is a robust plant with numerous clustered
pseudobulbs that are borne along a short, sometimes upwardly creeping, rhizome.
Nearly globose to ovoid or oblong-ovoid, the slightly compressed pseudobulbs are
7-9 (-18) cm long and 3.5-4 cm across. Somewhat 4-angled in cross-section, the
pseudobulbs are covered at the base with 2-4 sheathing leaves. The linear to
narrowly oblong, light yellowish green apical leaf (rarely 2) is 20-50 cm long
and (1.5-) 2.5-4 cm broad. An erect to arching paniculate, pyramidal
inflorescence is borne from the base of the recently matured pseudobulb and is
45-100 (-150) cm long. The panicle has a long peduncle and 8-12 branches in the
upper one-quarter to one-third. Each branch may bear 10-20 flowers that
individually last for about 10 days. The flowering period however, occurs over
an extended period as buds on the panicle open progressively.
Variable
in size and colour, the scentless flowers of Vtk.
excavata can be 38-45 mm across. The flowers have bright yellow sepals that
are variably blotched or barred with maroon to reddish-brown on the lower half.
Sometimes entirely yellow, the petals may be spotted with maroon to
reddish-brown in the lower half. Its three-lobed lip is vivid canary yellow and
bears a callus consisting of numerous tuberculate knobs in 3-5 ranks. The callus
is white with maroon to red-brown spots and the green column has yellow wings
that are spotted red.
Distributed in Ecuador, Bolivia
and Peru, Vtk. excavata
is a terrestrial plant that is found growing on rocks, grass and brush covered
lateritic red clay soils. It grows on steep slopes in moist montane forests
between (1,900-) 2,400-2,800 m altitude. An intermediate to cool-growing species
for subtropical regions, Vtk. excavata
requires cool summer temperatures with high humidity and good air circulation.
Grow it under 70% shade in a well-drained potting medium and keep it moist at
all times. Watering frequency can be reduced during the cooler months and while
it is not actively growing. The roots should not be allowed to remain dry for
long periods, so regular watering or misting will be needed during the winter.
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