Gasteria

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Gasteria
Gasteria pillansii var pillansii 1.jpg
Gasteria pillansii
Scientific classification e
Kingdom: Plantae
Clade: Angiosperms
Clade: Monocots
Order: Asparagales
Family: Asphodelaceae
Subfamily: Asphodeloideae
Tribe: Aloeae
Genus: Gasteria
Duval
Synonyms[1]

Ptyas Salisb.

Gasteria is a genus of succulent plants, native to South Africa (and the far south-west corner of Namibia).[1]

Naming[edit]

The genus is named for its stomach-shaped flowers ("gaster" is Latin for "stomach"). Common names include ox-tongue, cow-tongue, lawyer's tongue and, occasionally, mother-in-law's tongue.[2]

Description[edit]

Single flower of a Gasteria

Gasterias are recognisable from their thick, hard, succulent "tongue-shaped" leaves. Their inflorescence is also unique, with their curved, stomach-shaped flowers, which hang from inclined racemes.

Distribution[edit]

Gasteria rawlinsonii 'Staircase' (a cultivar) showing the distinctive pendulous, "stomach-shaped" Gasteria flowers

The species of this genus are mostly native to the Eastern Cape Province, South Africa, where the bulk of the species occurs – especially in the small area between Grahamstown and Uniondale which enjoys rainfall throughout the year. However distribution of several species extends widely across the low-altitude coastal regions of the country, in an arched horseshoe shape across South Africa. At the one end of the genus's distribution, a species Gasteria pillansii extends into the far south-west corner of Namibia. At the other end, a species reaches the Lebombo mountains of Swaziland.

Taxonomy[edit]

Distribution map of the various Gasteria species and subspecies in southern Africa

Gasteria is part of the family Asphodelaceae, subfamily Asphodeloideae. Closely related genera include Aloe and Haworthia, and the species of these genera are known to hybridise relatively easily with each other.[3]

Dividing Gasteria into species is extremely difficult, as each plant can be highly variable. One plant will look different depending on its location, its soil and its age. Young Gasteria plants typically look entirely different to older specimens. (Usually, young plants have flat, strap-shaped, highly tubercled leaves, in a distichous formation.) In addition, the species tend to flow into each other in gradual transitions, with many intermediate forms, rather than being cleanly divided into discrete and separate species. Lastly, hybrids occur easily and naturally, whenever the range of two species overlap in habitat.

There is therefore considerable disagreement on how many species exist, with as many as 100 names being listed. Current studies tend to agree that there are between 16 and 23 species.

Taxonomy according to flower morphology[edit]

Using morphology (especially flower structure), a traditional and widely accepted taxonomy was described in 1994 (van Jaarsveld et al.), dividing the genus into 2 sections, 4 series, and 21 species.

  • Section Longiflorae (2 series, 13 species)
    • Series Longifoliae (6 species):
      • Gasteria batesiana G.D.Rowley – Limpopo, Mpumalanga, KwaZulu-Natal
        • G. batesiana var. batesiana
        • G. batesiana var. dolomitica – Mpumalanga
      • Gasteria barbae van Jaarsv. – southern coast of Cape Province, between Knysna and Plettenberg Bay
      • Gasteria tukhelensis van Jaarsv. – KwaZulu-Natal
      • Gasteria croucheri (Hook.f.) Baker – south-east Cape Province to east KwaZulu-Natal
        • G. croucheri subsp. croucheri – south-east Cape Province to East KwaZulu-Natal
        • G. croucheri subsp. pendulifolia (van Jaarsv.) Zonn. – KwaZulu-Natal
        • G. croucheri subsp. pondoensis N.R.Crouch – south-east Cape Province
      • Gasteria acinacifolia (J.Jacq.) Haw. – southern coast of Cape Province
      • Gasteria polita van Jaarsv. – Cape Province
    • Series Multifariae (7 species):
      • Gasteria excelsa BakerTranskei, Eastern Cape
      • Gasteria pulchra (Aiton) Haw. – Cape Province
      • Gasteria carinata (Mill.) Duval – south-south-west Cape Province
        • G. carinata var. carinata – Langeberg in Cape Province
        • G. carinata var. retusa van Jaarsv. – Worcester & Heidelberg in Cape Province
        • G. carinata var. thunbergii van Jaarsv.=G. thunbergii N.E.Br.[4] – near Herbertsdale in Cape Province
        • G. carinata var. verrucosa van Jaarsv. – Bredasdorp in Cape Province
      • Gasteria nitida (Salm-Dyck) Haw. – southern Cape Province
        • G. nitida var. nitida – southern Cape Province
        • G. nitida var. armstrongii (Schönland) van Jaarsv. / G. armstrongii Schönland – southern Cape Province
      • Gasteria ellaphieae van Jaarsv. – Konga Dam in Cape Province
      • Gasteria glauca van Jaarsv – Cape Province
      • Gasteria vlokii van Jaarsv. – Great Swartberg + Witteberg in Cape Province (a higher altitude species)
  • Section Gasteria (2 series, 8 species)
    • Series Gasteria (7 species):
    • Series Namaquana (1 species):
      • Gasteria pillansii Kensit – Namibia, Cape Province
        • G. pillansii var. var. ernesti-ruschii (Dinter & Poelln.) van Jaarsv. – south-west Namibia to north-west Cape Province (Richtersveld)
        • G. pillansii var. hallii van Jaarsv. – western Cape Province
        • G. pillansii var. pillansii – western Cape Province

[6]

Taxonomy according to genome[edit]

A phylogenetic study in 2005[7] suggest that the genus may be sub-divided into 5 groups with respect to a increasing pattern in DNA content and geographical distribution:

Gallery for identification[edit]

Western distichous group[edit]

Species with distichous (two-ranked), strap-shaped leaves which are usually without keels.

Rare inland species[edit]

Large coastal group[edit]

Species generally form rosettes, with leaves usually bearing marginiform keels.

Cultivation[edit]

Gasteria species are grown in well-drained, sandy soils in light shade. The species can all be propagated by off-sets and cuttings (leaf cuttings can usually be rooted easily). They are also commonly propagated by seed. Germination usually occurs within 8 days but may take as long as one month depending on the species.

Flowering times vary between species, but is usually in the spring & summer. Those in the summer rainfall areas to the east, tend to always flower in spring to summer (October–January in South Africa) such as Gasteria batesiana, Gasteria croucheri & Gasteria acinacifolia. Those in the areas which receive rainfall all year, usually flower also in later summer (December–January) such as Gasteria excelsa, Gasteria nitida, Gasteria vlokii and Gasteria brachyphylla var. bayeri. Others in this region flower all year, but with a peak in the spring, such as Gasteria rawlinsonii, Gasteria bicolor & Gasteria carinata. The western-most species vary in their flowering times, within the species. Gasteria pillansii in the far west, flowers in summer (December–January), except for its northern-most variety "var. ernesti-ruschii" which flowers in autumn (March–April). Gasteria disticha usually flowers in spring, but in the far north of its range near Beaufort West it flowers in December.[8]

Gasteria species are prone to Fusarium root rot, if they are over-watered. [9][10]

Several hybrids with species in other related genera have been created in cultivation, such as between Gasteria and Aloe (×Gasteraloe), and between Gasteria and Haworthia (×Gasterhaworthia).

External links[edit]

References[edit]

  1. ^ a b Kew World Checklist of Selected Plant Families
  2. ^ Bailey, L.H.; Bailey, E.Z.; the staff of the Liberty Hyde Bailey Hortorium. 1976. Hortus third: A concise dictionary of plants cultivated in the United States and Canada. Macmillan, New York.
  3. ^ Stevens, P.F., Angiosperm Phylogeny Website: Asparagales: Asphodeloideae 
  4. ^ Govaerts, R. "Gasteria carinata var. thunbergii - Synonyms". World Checklist of Selected Plant Families. the Royal Botanic Gardens, Kew. Retrieved 18 February 2018. 
  5. ^ Govaerts, R. (2014). "Gasteria obliqua - Synonyms". World Checklist of Selected Plant Families. the Royal Botanic Gardens, Kew. Retrieved 18 February 2018. 
  6. ^ "Search term=Gasteria". World Checklist of Selected Plant Families. the Royal Botanic Gardens, Kew. Retrieved 18 February 2018. 
  7. ^ B. J. M. Zonneveld, E. J. van Jaarsveld: Taxonomic implications of genome size for all species of the genus Gasteria Duval (Aloaceae). 24 Feb 2005
  8. ^ E.J. van Jaarsveld: Gasterias of South Africa, A new revision of a major succulent group. Fernwood Press, Cape Town. p.19. ISBN 1-874950-01-6
  9. ^ Propagation of Gasterias
  10. ^ Gasteria