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Isoetes alstonii
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Photo: Petra Ballings
SRGH
Photo: Petra Ballings
SRGH
Photo: Bart Wursten
Near Danger Point, Victoria Falls National Park.
Photo: Bart Wursten
Near Danger Point, Victoria Falls National Park.
Photo: Bart Wursten
Near Danger Point, Victoria Falls National Park.
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Species details: Click on each item to see an explanation of that item (Note: opens a new window)
| Synonyms: | |
| Common names: | |
| Frequency: | |
| Status: | Native |
| Description: |
Pseudo-corm 10-20 cm in diameter, 2-lobed; bud scales vestigial or lacking. Leaves 10-40, linear, 130-400 mm × 1 mm (apically)- 6 mm (at base),apex tapering to a point, yellow to midgreen, semi-circular in cross-section, abruptly ovate-oblong at the base, with broadly hyaline wing, stomata present in upper parts of the leaves. Ligule 1-2 × c. 1.5 mm, hyaline, triangular, pointed. Velum very narrow, reduced to a thin marginal ring. Sporangia 4-10 × 3-6 mm. Megaspores of 2 sizes, 0.52 and 0.3 mm in diameter, dark grey, drying white, usually 3-radiate, with large warts below, granulated above. |
| Notes: | I. alstonii is distinguished from other species in our region by its 2-lobed pseudo-corm and a sporangium that is blackish when wet. |
| Derivation of specific name: | alstonii: named after A.H.G. Alston (1902-1958), Britisch botanist specialised in African pteridophytes. |
| Habitat: | Aquatic plant found in permanent water, at the edges of pools, in seasonally dry streambeds and pools, perennial in permanent mist spray of the Victoria Falls. |
| Altitude range: (metres) | 225 - 1310 m |
| Worldwide distribution: | Ethiopia, Mozambique, Namibia, Tanzania, Zambia, Zimbabwe. |
| Zimbabwe distribution: | W,S |
| Growth form(s): | Terrestrial. |
| Endemic status: | |
| Red data list status: | |
| Insects associated with this species: | |
| Spot characters: | Display spot characters for this species |
| Images last updated: | Thursday 16 December 2021 |
| Literature: |
Burrows, J.E. (1990). Southern African Ferns and Fern Allies. Frandsen, Sandton. Pages 36 - 37. (Includes a picture). Crouch, N.R., Klopper, R.R., Burrows, J.E. & Burrows, S.M. (2011). Ferns of Southern Africa, A comprehensive guide Struik Nature Pages 72 - 73. (Includes a picture). Jacobsen, W.B.G. (1983). The Ferns and Fern Allies of Southern Africa. Butterworths, Durban and Pretoria. Pages 154 - 155. (Includes a picture). Kornas, J. (1979). Distribution and ecology of the Pteridophytes in Zambia Polska Akademia Nauk Wydzial II Nauk Biologicznych Page 35. Reed, C.F. & Verdcourt, B. (1965). Isoetes alstonii, a new species of Isoetes from Rhodesia Kirkia 5(1) Pages 19 - 20. Protologue (Includes a picture). Roux, J.P. (2009). Synopsis of the Lycopodiophyta and Pteridophyta of Africa, Madagascar and neighbouring islands Page 8. Schelpe, E.A.C.L.E. (1970). Pteridophyta Flora Zambesiaca Page 30. (Includes a picture). |
Other sources of information about Isoetes alstonii:
Our websites:
Flora of Mozambique: Isoetes alstoniiFlora of Zambia: Isoetes alstonii
External websites:
African Plants: A Photo Guide (Senckenberg): Isoetes alstoniiBHL (Biodiversity Heritage Library): Isoetes alstonii
EOL (Encyclopedia of Life): Isoetes alstonii
GBIF (Global Biodiversity Information Facility): Isoetes alstonii
Google: Web - Images - Scholar
iNaturalist: Isoetes alstonii
IPNI (International Plant Names Index): Isoetes alstonii
JSTOR Plant Science: Isoetes alstonii
Mansfeld World Database of Agricultural and Horticultural Crops: Isoetes alstonii
Plants of the World Online: Isoetes alstonii
Tropicos: Isoetes alstonii
Wikipedia: Isoetes alstonii
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