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This species is accepted, and its native range is Ethiopia to S. Africa, Madagascar.
A specimen from Kew's Herbarium

[FTEA]

Lamiaceae (Labiatae), A.J. Paton, G. Bramley, O. Ryding, R.M. Polhill, Y.B. Harvey, M. Iwarsson, F. Willis, P.B. Phillipson, K. Balkwill, C.W. Lukhoba, D.F. Otieno, & R.M. Harley. Pycnostachys, G Bramleyshaped. Flora of Tropical East Africa. 2009

Type
Type: cultivated from seeds sent from Madagascar, collected by Bojer & Helsinger (K!, holo.)
Morphology General Habit
Annual herb, 0.7–1.5 m tall, becoming softly woody below
Morphology Stem
Stems erect, hollow, quadrangular, or rounded-quadrangular where woodier, pubescent with short eglandular hairs and red sessile glands
Morphology Leaves
Leaves opposite, sessile, often deflexed; blades narrowly elliptic to lanceolate 4.5–13 × 0.8–2.5 cm, serrate, apex acuminate, narrowed to a cuneate or shortly rounded base, subglabrous above, sparsely pubescent with short eglandular hairs on the margins and venation beneath, also with red sessile glands beneath
Morphology Reproductive morphology Inflorescences
Inflorescence dense, when in flower forming a very narrow conical shape, in fruit 28–47 × 8–12 mm; bracts subtending entire inflorescence lanceolate, 5–15 mm long in flower, extending to up to 60 mm in fruit, acute to acuminate, enclosing buds then becoming deflexed in flower, ciliate with short eglandular hairs, persistent through flowering stage; bracts subtending single flowers linear to lanceolate, 2.5–3 mm long, ciliate
Morphology Reproductive morphology Flowers Calyx
Calyx with tube 0.5–1 mm long at anthesis, outer surface with eglandular hairs and red sessile glands, inner surface with tiny triangular scales present between calyx lobes, these with more plentiful eglandular hairs; lobes 5, subulate, 1.5–2 mm long, somewhat winged near the base; fruiting calyx with tube ± 3 mm long, funnel-shaped, apparently not compressed or gibbous on any side, lobes ± patent to the tube, lengthening to 2–2.5 mm
Morphology Reproductive morphology Flowers Corolla
Corolla white, blue or pale purple, 4–5 mm long; tube with scattered eglandular hair and red sessile glands, narrow and parallel-sided for ± 1.5 mm, then curving downwards and broadening for ± 1.5 mm before opening into two lips; posterior lip shorter than anterior, 0.5–1 mm long, lobes more densely pubescent with eglandular hairs and red sessile glands; anterior lip ± 1.5 mm long, ± 1 mm deep, with eglandular hairs and red sessile glands more plentiful on the front of lip
Morphology Reproductive morphology Flowers Androecium Stamens
Stamens connate for ± 0.5 mm, exserted for ± 1 mm
Morphology Reproductive morphology Fruits
Nutlets subglobose but somewhat flattened, barely 1 mm long.
Ecology
Marshy ground, lake margins, among grasses and in reed beds, can be in water or floating ‘sudd’; 900–2350 m
Conservation
Least Concern: widely distributed in tropical Africa and Madagascar
Note
The very wet habitat of P. coerulea is quite unusual in Pycnostachys making the species distinct. It can also be recognised due to its very narrow inflorescence, very small corolla and its calyx, which is not gibbous or compressed on any side but funnel-shaped in fruit. In addition the leaves are distinctive as they tend to be deflexed and dry to show conspicuous tertiary venation. The species shows some variation in the length of the calyx lobes throughout its large distribution that extends to Madagascar, where the calyx lobes tend to be longer. One specimen ( Trapnell in Central Research Station 485) collected in the south of Zambia, is more pubescent than the other collections.
Distribution
Range: Congo-Kinshasa, Rwanda, Burundi, Ethiopia, Zambia, Botswana and Madagascar Flora districts: U2 U4 K3 K5 T1 T2

Native to:

Botswana, Burundi, Ethiopia, Kenya, Madagascar, Rwanda, Tanzania, Uganda, Zambia, Zaïre

Coleus stenostachys (Baker) A.J.Paton & Phillipson appears in other Kew resources:

Date Reference Identified As Barcode Type Status
Jan 1, 1939 Speke [s.n.], Uganda Pycnostachys coerulea K000405970 Unknown type material
Bequaert [5972], Congo, DRC Pycnostachys coerulea K000405741 Unknown type material
Madagascar Pycnostachys coerulea K000406006 Unknown type material

First published in PhytoKeys 129: 100 (2019)

Accepted by

  • Govaerts, R., Nic Lughadha, E., Black, N., Turner, R. & Paton, A. (2021). The World Checklist of Vascular Plants, a continuously updated resource for exploring global plant diversity. https://doi.org/10.1038/s41597-021-00997-6 Scientific Data 8: 215.

Literature

Kew Backbone Distributions

  • Paton, A.J., Bramley, G., Ryding, O., Polhill, R., Harvey, Y., Iwarsson, M., Willis, F., Phillipson, P., Balkwill, K., Lukhoba, C., Otiend, D & Harley (2009). Lamiaceae (Labiatae) Flora of Tropical East Africa: 1-430.
  • Paton, A.J., Bramley, G., Ryding, O., Polhill, R.M., Harvey, Y.B., Iwarsson, M., Otieno, D., Balkwill, K., Phillipson, P.B., Harley, R.M. & Willis, F. (2013). Flora Zambesiaca 8(8): 1-346. Royal Botanic Gardens, Kew.

Flora of Tropical East Africa
Flora of Tropical East Africa
http://creativecommons.org/licenses/by-nc-sa/3.0

Herbarium Catalogue Specimens
Digital Image © Board of Trustees, RBG Kew http://creativecommons.org/licenses/by/3.0/

Kew Backbone Distributions
The International Plant Names Index and World Checklist of Selected Plant Families 2021. Published on the Internet at http://www.ipni.org and http://apps.kew.org/wcsp/
© Copyright 2017 World Checklist of Selected Plant Families. http://creativecommons.org/licenses/by/3.0

Kew Names and Taxonomic Backbone
The International Plant Names Index and World Checklist of Selected Plant Families 2021. Published on the Internet at http://www.ipni.org and http://apps.kew.org/wcsp/
© Copyright 2017 International Plant Names Index and World Checklist of Selected Plant Families. http://creativecommons.org/licenses/by/3.0