Gunnera

Primary tabs

Gunnera

Description

Perennial, ± acaulous (sometimes colossal herbs with a stem up to 6 m by 20 cm ø in extra-Mal. spp.), (in Mal.) stoloniferous, with more or less creeping, sub- or slightly supraterranean, thick rhizome. Leaves radical (or in non-Mai. spp. tufted at the end of the stem), reniform-cordate to ovate-truncate, simple to lobed, crenate to compound-dentate, rarely entire, palminerved, often rugose, with more or less conspicuous, simple to much divided, sometimes ochrea-like ‘cataphylls’ in the very leaf-axil. Flowers ebracteolate, bisexual or unisexual, monoecious (or dioecious), if monoecious with ♂ flowers upwards and ♀ ones downwards and sometimes with ☿ in between. Sepals 2 (rarely in some flowers 3), or 0, equal or unequal, often cuspidate, whether or not caducous. Petals 2(-0), in ♀ 0, oblong to spathulate, more or less convex outside, glabrous to pilose, often soon caducous, longer than the sepals. Stamens 2; Panicle, raceme or spike mostly 1, axillary or pseudoterminal, simple or compound. Ovary 1-celled, urceolate to compressed-ovoid; Ovule 1. Fruit a drupe or nut-like, coriaceous to more or less fleshy or juicy, almost globular to 3-gonous;

Distribution

Antarctic:, Antarctica (Antarctica present) Asia-Tropical:, Lesser Sunda Is. absent; Malaya (Peninsular Malaysia absent) Australasia:, Tasmania (Tasmania present) Hawaiian Islands: present Madagascar: present New Zealand: present South and Central America: present South and tropical Africa: present continental Asia: absent
About 30-50 spp., in South and tropical Africa and Madagascar, Malesia, Tasmania, New Zealand, Antarctica, the Hawaiian Islands, and South and Central America; not in continental Asia and Australia; in Malesia: not found in the Malay Peninsula and the Lesser Sunda Islands. .

Morphology

The evaluation of the so-called ‘ligule’ or ‘stipules’ is still under dispute. Their development is various but specific; in G. magellanica they are very large, in the New Zealand species they are absent (SCHNEGG, l.c.). SKOTTSBERG () regarded them as cataphylls. The latter opinion seems unlikely as they are not contained in the leaf spiral as remarked by MATTFELD (), but axillary.

Taxonomy

SCHINDLER subdivided the genus into 5 subgenera, to which MATTFELD added a sixth mono-typic one from E. South America, Ostenigunnera MATTFELD (1933, l.c.) which is very distinct and deserves clearly subgeneric rank. The others are Misandra in South America, Panke in South America, Juan Fernandez, and Hawaii (20-30 spp.), Milligania in New Zealand and Tasmania (9 spp.), Pseudogunnera in Malesia (1 sp.), and Gunnera (subg. Perpensum) in Madagascar and East Africa (1 sp.).
The characters SCHINDLER used for this classification are the occurrence of stolons, the distribution of the sexes, the structure and size of the ‘cataphylls’, and the size of the plant. It seems to me that, Ostenigunnera excepted, the mutual similarity is so large that distinguishable taxa at most deserve sectional rank, the more so as distinctions are less sharp than presented by SCHINDLER. For example: within Milligania occur both species with monoecious and with monoecious or dioecious flowers. In Perpensum with bisexual flowers sometimes the upper are ♂, whereas in Pseudogunnera between the upper ♂ and lower ♀ sometimes ☿ flowers are found. As to size of leaves Pseudogunnera (G. macrophylla) displays an enormous variability in New Guinea, from 2½-70 cm, depending either on altitude or habitat, so that small specimens of G. macrophylla from New Guinea so much resemble Milligania that RIDLEY, who described such small specimens as a separate species, G. reniformis, promptly declared them to be allied to the Tasmanian G. cordifolia HOOK.f. of subg. Milligania.
I believe that the subdivision of Gunnera could be improved if only 2 subgenera are recognized: subg. Gunnera and subg. Ostenigunnera. The first might then be distinguished into two or three sections, viz sect. Gunnera, including subg. Perpensum, Pseudogunnera, and Milligania, and occurring in Africa, Madagscar, Malesia, Tasmania, and New Zealand, and sect. Panke, including subg. Panke, occurring in Central and South America, Juan Fernandez, and the Hawaiian Is. The affinity of the South American subg. Misandra is uncertain to me, it may be kept separate, or may be included within sect. Gunnera.
The name Panke which is still used as the name of a South American subgenus of Gunnera already occurs in a work by L. FEUILLÉE (), as part of a phrase name. This was post-Linnean literatim translated into German by G. L. HUTH (). In this rare work all plants are beautifully depicted and accompanied by phrase names preceding their description. There is of course no question that FEUILLÉE adhered to the binomial system, i.e. that he distinguished genera and species. The German literatim translation does neither, and from the introduction by HUTH appears that he merely published it as a translation, without himself having the intention to make any changes towards framing it according to the binomal nomenclature. Therefore, this translation has no nomenclature standing.
It must be admitted, though, that not long ago a ‘generic’ name from this work was rejected nomen-claturally, viz Urceolaria, obviously because D. L. DENHAM () stated in his proposal that HUTH'S names are effectively and validly published and ‘must’ be accepted. The members of the Committee on nomina generica conservanda have obviously not verified DENHAM'S statement on this rare work and were thus misled. In HUTH’S translation neither genera nor species were indicated as such; each single species had a different phrase name, or better, was indicated by a phrase indication. Nomen-claturally this translation cannot be used for post-Linnean validation and should be discarded. Consequently we have refrained from proposing Panke to be rejected in favour of Gunnera.

Citation

BADER - in Bot. Jahrb. 1961: maps.
MATTFELD, Ostenia. 1933: 102
LINNÉ - in Mant. 1767: 16
SCHINDL. - in Pfl. R. 1905: 104