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This species is accepted, and its native range is Central Peru.


Wood, J.R.I. Stenostephanus (Acanthaceae) in Peru. Kew Bulletin 74: 64 doi:10.1007/s12225-019-9843-0

With an area of occupancy of 32,000 km2 and an extent of occurrence of 1724.075 km2, based on Geocat, this species should be provisionally classified as Endangered (EN) according to IUCN guidelines. Although hill forest is vulnerable to clearance, some populations lie within the Yanachaga-Chemillén National Park, Tingo María National Park and the new Sierra del Divisor National Park and enjoy legal protection.
Endemic to Peru in the zone where Huánuco, San Martín and Ucayali meet, principally in the zone known as La Divisoria.
Moist hill forest 1200 – 1850 m 1150 – 1250 m in the Peruvian Andes.
Morphology General Habit
Subshrub to 2 m; stems dark green, glabrous
Morphology Leaves
Leaves subsessile to shortly petiolate; lamina 10 – 31 × 4 – 13 cm, oblong-elliptic, shortly acuminate, basally cuneate, sometimes decurrent onto a poorly differentiated petiole, margin slightly undulate, both surfaces glabrous or puberulent on abaxial veins, veins c. 11 pairs, adaxially with numerous cystoliths, abaxially pale; petioles (0 –) 0.5 – 5 cm
Morphology Reproductive morphology Flowers Androecium Stamens
Stamens exserted, filaments glabrous, anthers 4 mm
Morphology Reproductive morphology Flowers Calyx
Calyx 9 – 11 mm, 5-lobed to base, lobes linear, acute, 0.75 – 1 mm wide
Morphology Reproductive morphology Flowers Corolla
Corolla 3 – 4 cm long, crimson, wine-red, dark red, indistinctly 2-lipped, the lips minutely puberulent, the upper lip subacute, entire c. 6 – 8 mm long, lower lip similar but 3-toothed, the teeth triangular c. 1.25 mm long
Morphology Reproductive morphology Flowers Gynoecium
Style glabrous, stigma globose, ovary glabrous
Morphology Reproductive morphology Flowers Pedicel
Pedicels 5 – 6 mm
Morphology Reproductive morphology Fruits
Capsule clavate, 12 – 13 mm long, glabrous
Morphology Reproductive morphology Inflorescences
Inflorescence a dense, many-flowered thyrse, 7 – 17 × 6 – 7 cm; bracts at base of thyrse resembling small, sessile leaves, pubescent; rhachis glabrous to tomentellous; bracts at branching points 6 – 12 × 7 – 10 mm, ovate, subrhomboid or obovate, diminishing in size upwards, green, persistent, glabrous or ciliolate; dichasia sessile
Morphology Reproductive morphology Seeds
Seeds lenticular c. 2.5 mm long (?immature).
Amongst species found in Peru, Stenostephanus densiflorus is very distinct for the possession of two distinct characters — the very dense inflorescence and the prominent bracts at the main branching points of the thyrse. Similar bracts are found in a number of species such as S. lamprus (Leonard) J.R.I.Wood from Colombia or S. laxus (Wassh.) Wassh. from Ecuador, but S. densiflorus differs from most of these in the absence of a long, somewhat recurved upper lip as well as in the denser inflorescence. It is perhaps most similar to S. asplundii (Wassh.) Wassh. but the corolla is red, elongate-tubular, not suburceolate, 3 – 4 cm, not 18 mm long and minutely puberulent, not pilose. This species is named “densiflorus” because of the very dense inflorescence.
Peru, Ucayali, Coronel Portillo, Padre Abad, Cumbre de la Divisoria, 1500 – 1600 m, 8 Feb. 1978, J. Schunke V. 9864 (holotype US2949097; isotype US 2948849).

Native to:


Stenostephanus densiflorus J.R.I.Wood appears in other Kew resources:

First published in Kew Bull. 74(4)-64: 9 (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. Scientific Data 8: 215.


Kew Bulletin

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  • Daniel, T. (2006). Synchronous flowering and monocarpy suggest plietesial life history for neotropical Stenostephanus chiapensis (Acanthaceae). Proc. Calif. Acad. Sci. 57: 1011 – 1018.
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  • Lindau, G. (1914). Acanthaceae. In: R. Pilger (ed.), Plantae Uleanae. Notizbl. Königl. Bot. Gart. Berlin 6: 192 – 200.
  • Lindau, G. (1922). Neue Gattungen der Acanthaceen. Notizbl. Bot. Gart. Berlin-Dahlem 8: 142 – 144.
  • Nees von Esenbeck, C. G. (1847). Acanthaceae. In: A. P. de Candolle (ed.), Prodromus systematis naturalis regni vegetabilis 11: 46 – 519. Masson, Paris.
  • Ruiz, H. & Pavon, J. A. (1798). Flora Peruviana et Chilensis Vol. 1: 1 – 78. Gabrielis de Sancha, Madrid.
  • Rusby, H. H. (1927). Descriptions of new genera and species of plants collected on the Mulford Biological Exploration of the Amazon Valley 1921 – 1922. Mem. New York Bot. Gard. 7: 205 – 387.
  • Wasshausen, D. C. & Wood, J. R. I. (2001). Further discoveries in the genus Stenostephanus (Acanthaceae) in Bolivia. Harvard Pap. Bot. 6: 449 – 454.
  • Wasshausen, D. C. & ____ (2004). The Acanthaceae of Bolivia. Contr. U. S. Natl. Herb. 49: 1 – 152.
  • Wasshausen, D. C. (1985). New species of Hansteinia (Acanthaceae) from Colombia and Ecuador. Brittonia 37: 203 – 208.
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  • Wasshausen, D. C. (1999b). In: P. M. Jørgensen & S. León-Yánez (eds), Catalogue of the Vascular Plants of Ecuador. Monogr. Syst. Bot. Missouri Bot. Gard. 75: 1 – 1181.
  • Wasshausen, D. C. (2007). A checklist of the Acanthaceae collected in the “Sira Mountains” of Peru. Ann. Naturhist. Mus. Wien 108 B: 167 – 190.
  • Wasshausen, D. C. (2013). Acanthaceae. In: C. Persson & B. Stahl (eds), Flora of Ecuador, Vol. 179: 1 – 328. University of Gothenburg, Göteborg.
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Kew Backbone Distributions
The International Plant Names Index and World Checklist of Selected Plant Families 2021. Published on the Internet at and
© Copyright 2017 World Checklist of Selected Plant Families.

Kew Bulletin
Kew Bulletin

Kew Names and Taxonomic Backbone
The International Plant Names Index and World Checklist of Selected Plant Families 2021. Published on the Internet at and
© Copyright 2017 International Plant Names Index and World Checklist of Selected Plant Families.