Common name: Bower's Spider Orchid
Caladenia boweri D.L.Jones APNI*
Description: Terrestrial tuberous herb.
Flower stem to 30 cm tall, around 2.5 mm diameter, densely hairy with non-glandular multicellular trichomes 3 mm long. Sterile bract oblong-ovate with acuminate apex, 30 mm long by 7 mm wide, fused with stem at its base only, margins free, surface covered in short glandular and non-glandular trichomes. Fertile bract enclosing pedicel base, margins involute, oblong-ovate when flattened with acuminate apex, 15–20 mm long by 6–7 mm wide, surface covered in short glandular and non-glandular trichomes. Ovary narrowly ellipsoid, 10 mm long and 3 mm diameter, covered with short glandular trichomes. Flower 50–60 mm across widest spread, pink, with darker veins, and darker pink labellum. Dorsal sepal pink with 3–5 darker pink veins, erect, slightly concave, 45–50 mm long by 2.5–3.5 mm wide toward base, tapering toward apex, then broadening at an apical club 14–16 mm long with protruding dark brownish elliptical osmophore cells. Lateral sepals spreading horizontally at base, tending decurved in outer half, pink with 3–5 darker pink veins, 50–70 mm long and 5–6 mm wide toward base, tapering to the apex, then broadening slightly into a brown flattish club 14–20 mm long covered in osmophore cells. Petals pink with 3–5 darker veins, spreading horizontally at base, tending decurved in outer half, 35–40 mm long and 3.0–3.5 mm wide toward the base, tapering into an acuminate, non-clubbed apex. Labellum slightly darker pink with darker pink veins and reddish-pink calli and marginal teeth; obscurely three-lobed when flattened, overall shape is narrow-cordate, but with lateral margins below half way flared in such a way to mark a break in the curvature of the outline between the upper and lower halves, with the mid-lobe only comprising the upper half; 14–16 mm long and 9–11 mm wide when flattened; each lateral lobe margin (the margins below the labellum mid-point) with 14 or 15 thickened teeth 1.0–3.5 mm long, the teeth asymmetrically spathylate, with a conical apex; each margin of the labellum mid-lobe with 20–25 teeth, shorter than those on the lateral lobe margins, and become shorter, less distinct, and more crowded from the base to the apex of the mid-lobe margin; labellum base with 6 ovoid basal calli around 2 mm long each held erect on a narrow stalk; labellum surface with 6 rows of callii extending from the base, with the middle four rows extending into the labellum midlobe, calli tallest at base, decreasing in stature toward the apex, at the base similar in shape to the teeth on the labellum margin, asymmetrically spathulate with upper part conical and swept-forward, on the labellum midlobe shorter. Column erect 12–13 mm long by 5 mm wide, translucent pink, with short glandular trichomes around the base, basal glands ovoid around 1.2 mm diameter, yellow. Anther 2.5 mm long, shortly rostrate, green with yellow, red-washed, margins. Pollinarium falcate, 3 mm long and 1 mm diameter, yellow and mealy. Stigma 'oblate-circular' 3 mm diameter.
Flowering: Flowering observed in late October.
Distribution and occurrence: Known by a single individual which was observed, photographed, and collected in 1988 on Mt Canobolas. This species has not been seen since, despite dedicated searching.
The only known individual grew in open Eucalyptus forest with E. macrorhycha, E. dives and E. canobolensis with a grass dominated ground layer at an altitude of 1100-1200 m in a freely draining basalt-drived loam.
NSW subdivisions: CT
Caladenia boweri presents an interesting case where an orchid possessing an unusual combination of characters and known by only a single individual has been described as a distinct species. Caladenia boweri is distinct in its pink flowers, three-lobed labellum, and petals that lack clubs, while the dorsal and lateral sepals have well-defined clubs. The three-lobed labellum and pink flowers separate C. boweri from C. fitzgeraldii, and the absence of clubs on the petals distinguishes C. boweri from C. leptoclavia, C. venusta, and a number of other spiders. Caladenia boweri shares pink flower colour and three-lobed labellum with 6 rows of calli with C. concolor but differs by the presence of defined clubs on the sepals, the lighter colour on the petals and labellum, and perhaps by the more sharply defined marginal teeth on the labellum mid-lobe. More observations of this species are required to establish its relationships to other spider Caladenia, and indeed confirm its continued existence in the wild.
Text by Matt A.M. Renner based on Jones (2019)
Taxon concept: Jones DL (2019) Two threatened new species of Orchidaceae from Mt Canobolas in central-western New South Wales. Australian Orchid Review 89(6): 36-41.
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