Primary tabs



Large herbs or shrubs, with cystoliths. Stems quadrangular and articulated. Leaves opposite, petiolate; blades elliptic to narrowly ovate, with numerous cylindrical cystoliths, margins entire or irregularly dentate. Inflorescences narrow, terminal and axillary, panicles, basal branchlets once or twice dichasially branched; bracts small, basal pair sometimes leaf-like; bracteoles none. Flowers homostylous, pedicellate; calyx campanulate, basally unequal and shortly 5-lobed or toothed; corolla tubular, slightly curved, limb short, 2-lipped, not spreading, upper lip 2-lobed, lobes contorted in buds; stamens 4, didynamous, inserted near apex of corolla tube, included in corolla tube or exserted from mouth of corolla, filaments united in pairs at base, anthers 2-thecous, thecae subequal to subparallel, obtuse at base, connective apiculate; disk annular, with distinct projections. Capsules clavate, retinacula present, septa with curved retinacula remaining attached to inner wall of mature capsule; seeds 6, homomorphic, flattened to lenticular.


Amazonian Brazil present, tropical moist forests of the Guianas present
A segregate with 3 species of the large genus Ruellia; local and infrequent at low elevation in tropical moist forests of the Guianas and adjacent Amazonian Brazil.


P. fulgens.


Growth rings absent.
Vessels distributed in radial strokes, solitary for 25%, remainder in radial multiples of 2-4, seldom in clusters; 36 (33-41) per sq. mm, outline round, diameter 30-60 µm. Vessel member length 800 (400-1120) µm. Perforations simple, intervascular pits 4 µm, slits included, at vessel tips indication of spiral thickening. Vessel/ray pitting irregular: small and round as well as large and elongate, almost scalariform. Thin tyloses present, some containing cystoliths.
Rays 1-4-seriate, 7 (3-9) per mm. Strongly heterogeneous, procumbent cells virtually absent, square cells few, upright cells up to 260 µm high; often vertically fused. Sheath cells often locally present. Contents: numerous cystoliths.
Parenchyma very scarce, occasionally a strand bordering a vessel. Strands of 2 cells and also undivided fusiform cells present.
Ground tissue consisting of septate fibres. Diameter 20-30 µm, walls thin 3-4 µm. Pits simple, numerous in radial and tangential walls. Length 805 (400-1120) µm. F/V ratio: 1.33.