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Synonyms: Isotoma sp. 'Cuttabri' (R.W. Jobson RWJ 1540) APNI*

Description: Annual (or possibly rarely a short-lived perennial) herb to c. 25 cm high, single-stemmed or occasionally with several stems arising from base. Stems erect or ascending, glabrous, sometimes producing adventitious roots from lower nodes.

Leaves linear-subulate or lowermost linear-lanceolate, 5–21 mm long, 0.4–3 mm wide, glabrous, entire or lower leaves with irregularly placed small marginal swellings, apex narrowly acute to subacute, often with a tiny translucent apiculum, base attenuate.

Flowers bisexual, each initially developing in the axil of one leaf of a sub-opposite pair of distal leaves, the axis between the sub-opposite leaves subsequently elongating so that the leaves are displaced and appear alternate, this pattern repeating with subsequent terminal growth so that a flower appears to be borne at every second node, lateral flower-bearing shoots sometimes produced from the ‘non-flowering’ nodes if conditions favourable for flowering persist; pedicels 16–55 mm long, glabrous. Calyx lobes 1.5–2.5 mm long. Corolla weakly 2-lipped, 10–14 mm long; upper lip two-lobed, violet-blue; lower lip three-lobed, the lobes basally fused for c. 2–3.5 mm above the sinus between the two lips, the fused part with a prominent central yellow zone and 3 deep purple, ±basally fused broad bands, deep purple bands extending into the tube on the ventral side and covered with dense club-shaped hairs; central lobe violet-blue distally, white proximally; lateral lobes mostly violet-blue but white proximally on the half adjacent to the central lobe; tube 5–7 mm long, split to within 3.5–4.8 mm of base on dorsal side, glabrous externally, internally with dense club-shaped hairs on the ventral side covering the deep purple vertical bands and yellow zone adjacent and immediately below, longer hairs to c. 0.3 mm present further below in the proximal region of the tube. Anther tube dark greyish-blue, 1.5–1.9 mm long, two lower anthers each with an apical seta c. 0.3–0.5 mm long.

Fruit obconical to obovoid, slightly compressed laterally, 3.3–5 mm long. Seeds subcylindrical to ellipsoid or ovoid, subterete to slightly compressed, 0.38–0.5 mm long, mid to dark brown, with a network of almost straight to heterogeneously undulating close fine surface ridges.

Habit Photo Jaime Plaza

Flower Photo J.Plaza

Other photo Photo rwjobson

Flowering: Length of flowering season is dictated by rainfall and temperature patterns.

Distribution and occurrence: Known from a very restricted area in the vicinity of Cuttabri, New South Wales.

Occurs in sedge-dominated wetlands occupying shallow basins on the Namoi River floodplain.
NSW subdivisions: NWP

Threatened species: NSW BCA: Critically Endangered

AVH map***

A final determination to list this species as Critically Endangered under the NSW Biodiversity Conservation Act 2016 (NSW BCA 2016) was made on 24 September 2021.

The characteristics that distinguish Lobelia claviflora from species of Isotoma (and those Lobelia that have an entire or very weakly cleft corolla tube) are the erect habit, very narrow mostly entire glabrous leaves, distinctive arrangement of colour zones on the corolla including large white zones on the lower three lobes (white zone occupying approximately the proximal half of the central lobe) and deep purple bands in the throat that are covered with short dense club-shaped hairs, and seeds with a network of almost straight to heterogeneously undulating close, fine surface ridges. It is most likely to be confused with I. gulliveri F.Muell., I. luticola Carolin or L. douglasiana F.M.Bailey (syn. I. armstrongii E.Wimm.).