Gasteria

Classification System: APG IV

Superregnum: Eukaryota
Regnum: Plantae
Cladus: Angiosperms
Cladus: Monocots
Ordo: Asparagales

Familia: Asphodelaceae
Subfamilia: Asphodeloideae
Genus: Gasteria
Sectiones: G. sect. Gasteria – G. sect. Longifoliae

Species: G. acinacifolia – G. barbae – G. batesiana – G. baylissiana – G. brachyphylla – G. carinata – G. croucheri – G. disticha – G. doreeniae – G. ellaphieae – G. excelsa – G. glauca – G. glomerata – G. loedolffiae – G. nitida – G. obliqua – G. pillansii – G. polita – G. pulchra – G. rawlinsonii – G. tukhelensis – G. vlokii

Nothospecies: G. × cheilophylla
Name

Gasteria Duval, Pl. Succ. Horto Alençon. 6. (1809)
Type species: Gasteria disticha (L.) Haw., Philos. Mag. Ann. Chem. 2: 351 (1827) originally designated as synonym Gasteria angustifolia Duval, Pl. Succ. Horto Alencon. 6. (1809), vide Maire (1958).

Synonymy

Homotypic
Aloe sect. Gasteria [as Gasteriae] (Duval) Salm-Dyck, Aloes Mesembr. 1: sect. 29. (1836)
Heterotypic
Aloe sect. Curviflorae Haw., Trans. Linn. Soc. London 7: 12. (1804)
Gasteria sect. Breviflorae Haw., Saxifrag. enum. 2: 47. (1821), nom. nud.
Gasteria sect. Longiflorae Haw., Saxifrag. enum. 2: 47. (1821), nom. nud.
Gasteria sect. Mediocres Haw., Saxifrag. enum. 2: 47. (1821), nom. nud.
Ptyas Salisb., Gen. Pl. 76. (1866)
Type species: Ptyas disticha (L.) Salisb., nom. inval.

References

Duval, H.A. 1809. Plantae succulentae, in Horto Alenconio 6.
Govaerts, R. et al. 2017. Gasteria in World Checklist of Selected Plant Families. The Board of Trustees of the Royal Botanic Gardens, Kew. Published online. Accessed: 2017 Sept. 14. Reference page.
International Plant Names Index. 2017. Gasteria. Published online. Accessed: Sept. 14. 2017.
Maire, R.C.J.E. 1958. Fl. Afrique N. 5-6: 71.
Manning, J.C. Boatwright, J.S., Daru, B.H., Maurin, O. & van der Bank, M. 2014. A molecular phylogeny and generic classification of Asphodelaceae subfamily Alooideae: a final resolution of the prickly issue of polyphyly in the alooids? Systematic Botany 39(1): 55–74. DOI: 10.1600/036364414X678044 ResearchGate Reference page.
USDA, ARS, Germplasm Resources Information Network. Gasteria in the Germplasm Resources Information Network (GRIN), U.S. Department of Agriculture Agricultural Research Service. Accessed: 09-Oct-10.

Vernacular names
suomi: Sarviaaloet

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

Naming

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
Single flower of a Gasteria
Gasteria brachyphylla

Gasterias are recognisable from their thick, hard, succulent "tongue-shaped" leaves. These are either in two opposite ranks (distichous), or in various distinctive spiral arrangements.[3] Their inflorescence is also unique, with their curved, stomach-shaped flowers, which hang from inclined racemes.
Distribution
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 occur – especially in the small area between Makhanda 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 Eswatini.
Taxonomy
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.[4]

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 from 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.
Taxonomy according to flower morphology

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 16 species. E. J. van Jaarsveld has revised the taxonomy since then and the most recent synoptic review was published in 2007.[5] Several new species have been described in recent years, as well. Currently the number of accepted species is 29.

Section Longiflorae (2 series, 19 species)
Series Longifoliae (6 species):
Gasteria acinacifolia (J.Jacq.) Haw. – southern coast of Cape Province
Gasteria barbae van Jaarsv. – southern coast of Cape Province, between Knysna and Plettenberg Bay[6]
Gasteria batesiana G.D.Rowley – Limpopo, Mpumalanga, KwaZulu-Natal
G. batesiana var. batesiana G.D.Rowley
G. batesiana var. dolomitica van Jaarsv. & A.E.van Wyk – Mpumalanga
Gasteria croucheri Baker – south-east Cape Province to east KwaZulu-Natal
G. croucheri subsp. croucheri Baker – south-east Cape Province to East KwaZulu-Natal
G. croucheri subsp. pendulifolia (van Jaarsv.) Zonn. – KwaZulu-Natal
G. croucheri subsp. pondoensis N.R.Crouch, Gideon F.Sm. & D.Styles – south-east Cape Province[7]
Gasteria loedolffiae van Jaarsv. – Eastern Cape[8]
Gasteria tukhelensis van Jaarsv. – KwaZulu-Natal

Series Multifariae (13 species):
Gasteria armstrongii Schönland – southern Cape Province
Gasteria carinata (Mill.) Duval – south-south-west Cape Province
G. carinata var. carinata (Mill.) Duval – Langeberg in Cape Province
G. carinata var. glabra (Salm-Dyck) van Jaarsv. – Mossel Bay to Gouritz River
G. carinata var. verrucosa (Mill) van Jaarsv. – Bredasdorp in Cape Province
Gasteria ellaphieae van Jaarsv. – Kouga Dam in Cape Province
Gasteria excelsa Baker – Transkei, Eastern Cape
Gasteria glauca van Jaarsv. – Kouga River Valley
Gasteria koenii van Jaarsv. – Swartberg[9]
Gasteria langebergensis (van Jaarsv) van Jaarsv. & Zonn. – western Cape Province[10]
Gasteria nitida Haw. – southern Cape Province
Gasteria polita van Jaarsv. – Cape Province
Gasteria pulchra Haw. – Cape Province
Gasteria thunbergii N.E.Br. – near Herbertsdale in Cape Province
Gasteria visserii van Jaarsv. – Eastern Cape[11]
Gasteria vlokii van Jaarsv. – Great Swartberg + Witteberg in Cape Province (a higher altitude species)

Section Gasteria (2 series, 10 species)
Series Gasteria (9 species):
Gasteria baylissiana Rauh – Suurberg Range in Cape Province
Gasteria bicolor Haw. – south-east Cape Province; naturalized in Mexico
G. bicolor var. bicolor Haw.
G. bicolor var. fallax (Haw.) van Jaarsv.
G. bicolor var. liliputana (Poelln.) van Jaarsv.
Gasteria brachyphylla (Salm-Dyck) van Jaarsv. – Little Karoo in Cape Province
G. brachyphylla var. brachyphylla (Salm-Dyck) van Jaarsv.
G. brachyphylla var. bayeri van Jaarsv. – Little Karoo in Cape Province
Gasteria camillae van Jaarsv. & Molteno – Baviaanskloof mountain range[12]
Gasteria disticha (L.) Haw. – Robertson Karoo and surrounds, Western Cape
G. disticha var. disticha (L.) Haw. – south-west and south-central Cape Province
G. disticha var. robusta van Jaarsv. – western Cape Province
Gasteria doreeniae van Jaarsv. & A.E.van Wyk – Cape Province
Gasteria glomerata van Jaarsv. – Kouga Dam in Cape Province
Gasteria rawlinsonii Oberm. – Baviaanskloof in Cape Province
Gasteria retusa (van Jaarsv.) van Jaarsv. – Worcester & Heidelberg in Cape Province

Series Namaquana (1 species):
Gasteria pillansii Kensit – Namibia, Cape Province
G. pillansii var. pillansii Kensit – western Cape Province
G. pillansii var. ernesti-ruschii (Dinter von Poellnitz) van Jaarsv. – south-west Namibia to north-west Cape Province (Richtersveld)
G. pillansii var. hallii van Jaarsv. – western Cape Province

Taxonomy according to genome

A phylogenetic study in 2005[13] suggest that the genus may be sub-divided into 5 groups with respect to an increasing pattern in DNA content and geographical distribution:

Group A
Gasteria rawlinsonii (possibly a relict species; genetically an outlier, with the smallest genome)
Group B - 8 rare and restricted inland species (possibly also relict species, with relatively small genomes):
Gasteria armstrongii (separated from G. nitida here due to the difference in DNA content)
Gasteria polita
Gasteria glomerata
Gasteria pulchra
Gasteria ellaphieae
Gasteria vlokii
Gasteria glauca
Gasteria nitida
Group C - 5 widespread, distichous species, mainly from the west of southern Africa:
Gasteria brachyphylla
Gasteria bicolor
Gasteria disticha
Gasteria baylissiana
Gasteria pillansii
Group D - 5 widespread, rosette-forming species, mainly large coastal species:
Gasteria excelsa
Gasteria croucheri (including Gasteria pendulifolia)
Gasteria acinacifolia
Gasteria carinata
Group E
Gasteria batesiana (most northerly species, with the largest genome)

Gallery for identification

Gasteria rawlinsonii has long hanging stems. Its leaves have a rough surface.

Western distichous group

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

Gasteria pillansii has rough, mat-surfaced leaves with larger elongated flowers

The larger elongated Gasteria pillansii flowers

Gasteria disticha has rough, mat-surfaced (often wavy edged) leaves

The smaller, rounded Gasteria disticha flowers

Gasteria brachyphylla has smooth-surfaced, glossy leaves with crenulate margins.

Gasteria bicolor eventually develops a short, sprawling stem. It has smooth, shiny, erect leaves

Gasteria baylissiana has distinctive tiny, white, truncate tubercles on both sides of its swollen, convex leaves, that have squarely truncated leaf-tips.

Rare inland species

Gasteria glauca has rough-surfaced, blue-green leaves.

Gasteria ellaphieae forms rosettes of pointed, triangular, recurved, densely tuberculate leaves, and branched inflorescence.

Gasteria glomerata has distichous compact, round, glaucous, recurved rough-surfaced leaves, and forms dense clumps.

Gasteria vlokii forms rosettes of mat-surface, slightly rough, triangular (usually recurved), strap shaped leaves.

Adult Gasteria nitidas form rosettes of smooth, shiny, triangular leaves, with smooth (non-serrated) edges and true (non-marginiform) keels. Juvenile plants have recurved distichous, tubercled leaves.

Gasteria armstrongii is a very divergent form of Gasteria nitida which maintains into adulthood the dark, recurved, retuse, distichous, roughly tuberculate leaves.

Gasteria polita forms rosettes of short, triangular, smooth leaves, with rounded ends and strong keels

Gasteria doreeniae

Gasteria pulchra forms rosettes of smooth, thin, sharp, elongated, ascending leaves (linear triangular).

Large coastal group

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

Gasteria carinata var carinata – the typical form. It has erect & spreading, rough, sparsely bumpy/tuberculate leaves

Gasteria carinata var carinata – the adult form with juvenile

Gasteria carinata var verrucosa is a proliferous variety with erect & spreading leaves that remain distichous and heavily tubercled into adulthood

Gasteria acinacifolia has slender, erect & spreading leaves with finely serrated edges. Heavily spotted.

Gasteria excelsa has smooth spreading leaves with a darker colour and sharply serrated edges.

Gasteria croucheri has smooth spreading, dark green, slightly glaucous leaves

Gasteria tukhelensis has slender, smooth and shiny leaves

Gasteria batesiana has leaves which are heavily tuberculate (bumpy/warty) and finely rululous (wrinkled).

Cultivation

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 westernmost species vary in their flowering times, within the species. Gasteria pillansii in the far west, flowers in summer (December–January), except for its northernmost 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.[14]

Gasteria species are prone to Fusarium root rot, if they are over-watered. [15][16]

The cultivar 'Little Warty' [17] is a recipient of the Royal Horticultural Society's Award of Garden Merit.

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).
References

Kew World Checklist of Selected Plant Families
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.
Molteno, S. (2022). Phyllotaxis in Asphodelaceae subfam. Alooideae: a tool in taxon delimitation. Haseltonia, 28(1), https://doi.org/10.2985/026.028.0107
Stevens, P.F., Angiosperm Phylogeny Website: Asparagales: Asphodeloideae
van Jaarsveld, E. J. (2007). The genus Gasteria: a synoptic review (new taxa and combinations), Aloe, 44 (4), pp. 81-104.
van Jaarsveld, E. J. (2014). Gasteria barbae, a new cliff-dwelling species from the Western Cape, South Africa, CactusWorld, 32 (4), pp. 257-260.
Crouch, N.R., Smith, G.F. and Styles, D.G.A. (2011). Gasteria croucheri subsp. pondoensis, a new cremophyte from Pondoland, South Africa, Bothalia, 41, pp. 183-185.
van Jaarsveld, E. J. (2014). Gasteria loedolffiae (Asphodelaceae). A new cliff-dwelling species from the Eastern Cape, South Africa, Bradleya, 32, pp. 44-49.
van Jaarsveld, E. J. (2017). Gasteria koenii, a New Gasteria Species from the Swartberg, Western-Cape, South Africa. Haseltonia, 23, pp. 48-52.
van Jaarsveld, E.J., Zonneveld, B.J.M., and Tribble, D.V. (2019). Gasteria langebergensis, a new status for a Gasteria from the Western Cape, South Africa. Bradleya, 37, pp. 167-171.
van Jaarsveld, E. J. (2020). Gasteria visserii van Jaarsv., a new species from the Eastern Cape, South Africa. Bradleya, 38, pp. 26-29.
van Jaarsveld, E. J. and Molteno, S. (2020). Gasteria camillae van Jaarsv. & Molteno, a new obligatory cliff-dwelling species from the Eastern Cape, South Africa. Bradleya, 38, pp. 20-25.
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
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
Propagation of Gasterias
Gasteria
"Gasteria 'Little Warty'". RHS. Retrieved 8 July 2020.