Urticaceae
Pilea

Pilea johnstonii Oliv.

First published in Trans. Linn. Soc. London, Bot. 2: 349 (1887)
This species is accepted
The native range of this species is SE. Ethiopia to E. Zimbabwe. It is a subshrub or epiphyte and grows primarily in the wet tropical biome.

Descriptions

Urticaceae, I. Friis. Flora Zambesiaca 9:6. 1991

Morphology General Habit
Perennial herbs with short, creeping rhizomes and erect unbranched or little branched juicy stems up to 0.4 m. tall, monoecious.
Morphology Leaves
Leaves of a pair subequal, 2–6 x 1.5–4.5 cm., broadly ovate to ovate-lanceolate; apex acuminate; base cuneate, obtuse, truncate or rounded, rarely subcordate; margin coarsely serrate, with 7–15(24) teeth on each side, lamina upper surface with scattered stiff hairs and linear cystoliths, lower surface glabrous to densely pubescent, especially on the nerves.
Morphology Leaves Petiole
Petiole 0.3–5(10) cm. long, usually pubescent.
Morphology Leaves Stipules
Stipules brown, membranous, up to 5(8) mm. long, broadly ovate, with a rounded or cordate base, persisting.
Morphology Reproductive morphology Inflorescences
Inflorescences axillary, with up to 4 inflorescences at each node, flowers arranged in pedunculate heads or interrupted spikes, with 2–6 globular heads along the axis of each spike, or with a branched inflorescence axis. Male heads up to 8( 12) mm. in diam. on peduncles up to 6 cm. long; male flowers on pedicels up to 2 mm. long, 4-merous, with apiculate tepals (sometimes developed into horn-like appendages). Female heads up to 6 mm. in diam., subsessile or on peduncles up to 5 cm. long; female flowers on pedicels 1–2 mm. long, 3-merous, tepals with appendages as in the male flowers, middle tepal lanceolate, up to 3 mm. long, lateral tepals shorter.
sex Male
Male heads up to 8( 12) mm. in diam. on peduncles up to 6 cm. long; male flowers on pedicels up to 2 mm. long, 4-merous, with apiculate tepals (sometimes developed into horn-like appendages).
sex Female
Female heads up to 6 mm. in diam., subsessile or on peduncles up to 5 cm. long; female flowers on pedicels 1–2 mm. long, 3-merous, tepals with appendages as in the male flowers, middle tepal lanceolate, up to 3 mm. long, lateral tepals shorter.
Morphology Reproductive morphology Fruits
Achene compressed ovoid, lanceolate, smooth, shiny, brown, up to 2 mm. long.
[FZ]

Urticaceae, I. Friis University of Copenhagen, Denmark. Flora of Tropical East Africa. 1989

Morphology General Habit
Perennial herb with prostrate and ascending stems, up to 0.6 m. high.
Morphology Stem
Stems juicy, glabrous.
Morphology Leaves
Leaves of a pair subequal; stipules ovate or triangular, prominent, brown, membranous, (1.5–)3–7.5(–8.5) mm. long, 0.8–4 mm. wide, base subcordate, apex rounded; petioles 0.3–8(–10) cm. long, glabrous or with a few scattered spreading hairs near the connection with lamina; lamina broadly ovate to ovate, rarely elliptic or lanceolate, (1–)1.5–8.5(–12.5) cm. long, (0.8–)l–7.5(–8.5) cm. wide, base cuneate, truncate or subcordate, margin serrate, with 6–24 teeth on each side, apex short-acuminate; lateral nerves 4–10, basal pair reaching 4th–7th(–10th) tooth from the apex; glabrous on both surfaces or with spreading hairs on the nerves on the lower surface, upper surface with regularly arranged linear cystoliths, lower surface sometimes with clearly marked hydatodes.
Morphology Reproductive morphology Inflorescences
Male inflorescences (heads) 5–12 mm. in diameter, on peduncles 0.8–6 cm. long; ♀ inflorescences (heads) subsessile or on peduncles 1–5 cm. long, 4–10 mm. in diameter. Inflorescences usually 2 together in the upper leaf-axils, always consisting of a ± pedunculate corymbose head, but sometimes with 2 side-branches below the head, rarely with repeated further branching under each head and up to 7 heads on each peduncle.
sex Male
Male flowers on pedicels 0.8–2 mm. long; perianth ± 1 mm. in diameter, 4-merous; tepals with up to 0.5 mm. long subapical appendages.
Morphology Reproductive morphology Flowers
Female flowers subsessile; perianth 0.8(–l) mm. long, middle lobes the largest, with subapical appendage. Male flowers on pedicels 0.8–2 mm. long; perianth ± 1 mm. in diameter, 4-merous; tepals with up to 0.5 mm. long subapical appendages.
sex Female
Female flowers subsessile; perianth 0.8(–l) mm. long, middle lobes the largest, with subapical appendage.
Morphology Reproductive morphology Fruits
Achene ovoid 0.8–1 mm. long, often with a ± marked flattened edge.
[FTEA]

IUCN Red List of Threatened Species https://www.iucnredlist.org/species/103646614/103648332

Conservation
LC - least concern
[IUCN]

Extinction risk predictions for the world's flowering plants to support their conservation (2024). Bachman, S.P., Brown, M.J.M., Leão, T.C.C., Lughadha, E.N., Walker, B.E. https://nph.onlinelibrary.wiley.com/doi/full/10.1111/nph.19592

Conservation
Predicted extinction risk: not threatened. Confidence: confident
[AERP]

Sources

  • Angiosperm Extinction Risk Predictions v1

    • Angiosperm Threat Predictions
    • http://creativecommons.org/licenses/by/4.0

  • Flora Zambesiaca

    • Flora Zambesiaca
    • http://creativecommons.org/licenses/by-nc-sa/3.0

  • Flora of Tropical East Africa

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

  • Herbarium Catalogue Specimens

    • 'The Herbarium Catalogue, Royal Botanic Gardens, Kew. Published on the Internet http://www.kew.org/herbcat [accessed on Day Month Year]'. Please enter the date on which you consulted the system.
    • Digital Image © Board of Trustees, RBG Kew http://creativecommons.org/licenses/by/3.0/

  • IUCN Categories

    • IUCN Red List of Threatened Species
    • http://creativecommons.org/licenses/by-nc-sa/3.0

  • Kew Backbone Distributions

    • The International Plant Names Index and World Checklist of Vascular Plants 2025. Published on the Internet at http://www.ipni.org and https://powo.science.kew.org/
    • © Copyright 2023 World Checklist of Vascular Plants. http://creativecommons.org/licenses/by/3.0

  • Kew Names and Taxonomic Backbone

    • The International Plant Names Index and World Checklist of Vascular Plants 2025. Published on the Internet at http://www.ipni.org and https://powo.science.kew.org/
    • © Copyright 2023 International Plant Names Index and World Checklist of Vascular Plants. http://creativecommons.org/licenses/by/3.0