The genus Melica L . ( Poaceae ) in southern Africa

Two species are recognized in this revision of the genus Melica. Both species belong to the subgenus Melica, and are the only representatives of the genus in Africa south of the Sahara. Five species formerly recognized have been reduced to synonymy.


INTRODUCTION
In Species Plantarum (1753), Linnaeus described three species in Melica, all from the northern hemisphere.The first southern African species were described by Thunberg in the Prodromus of 1794, where he assigned six species to the genus, but in Flora Capensis of 1823 he correctly moved four of these to Ehrharta, leaving the two Melica species presently recognized.Additional species were described over the years by Schrader (1821), Lehmann (1821), Nees (1841) and Stapf (1900 and1910), so that by the time of Flora Capensis, Stapf (1900) recognized six species.Following Stapf, Chippindall (1955) accounted for seven species, but gave a key to only the two Thunberg species, and implied doubt about the status of the other five, which are here reduced to synonymy.
Melica was not typified by its author (Linnaeus, 1754), and two proposals have been made for a lectotype.Nash in Britton & Brown (1913) put forward M. ciliata as the lectotype.Hitchcock & Green (1929) suggested instead that the Standardspecies should be M. nutans, on the grounds that Linnaeus first used the generic name Melica in Flora Lapponica in 1737, and the species there was M. nutans.The Nash proposal can be superseded by the Hitchcock & Green proposal on the grounds that all the lectotypes set out in Britton & Brown (1913) were selected arbitrarily (Stafleu, 1978).The Index Nominum Genericorum accepts M. nutans as the lectotype species for the genus.
Melica is a classical name that was adopted by Linnaeus for this genus.Theophrastus applied it to an unknown species of Sorghum, and in Italy the name today is used for A kind of Sorghum with sweet juice (mel = honey).Hempel (1970 and1973) Tateoka (1957), where it is included in the subfamily Arundoideae.However, he later moved the tribe, consisting of the genera Glyceria, Pleuropogon, Schizachne, Streblochaete and Lycochloa, to the Festucoideae (Tateoka, 1965).

DISTRIBUTION
A genus of about 70 species, Melica is widespread in temperate areas except Australia.The northern hemisphere distribution encircles the earth, north of the tropic of Cancer.The southern hemisphere distribution is disjunct from the northern hemis phere, with one area in South America and another in southern Africa.The southern African species are geographically the most isolated.The nearest species on the continent are in northern Algeria and Morocco, and the nearest in the southern hemis phere are in South America.(Hempel, 1970).

MORPHOLOGY
Both southern African species of Melica grow in compact many-stemmed clumps, with short thin rhizomes, which are buried as much as 150 mm.The culms may branch below the soil surface, so that in a large plant there is a tough net-like mass of rhizomes and culm bases.The leaf sheaths and blades are scabrous with fine retrorse hairs.In M. decumbens the leaf blades are always strongly scabrous.M. racemosa most often has scabrous leaf blades also, but sometimes the leaves may be glabrous or velvety, or with scattered hairs on the upper surface.This condition is so characteristic of Melica that the genus may be recognized in the field by the texture of the leaves even when the plants are not flowering.In the past taxa have often been confused because of differences in the appearance of the leaf blades on herbarium specimens.In nature, the plants usually have their leaf blades expanded with the lamina held flat or slightly curved upward at the margins and the base rounded.However, as soon as the plants are damaged the blades quickly roll up so that they appear nearly filiform, and the rounded base is not obvious.For this reason, specimens of the same taxon may appear quite different on a herbarium sheet, depending on how quickly they were pressed after collection.
The inflorescence is a narrow, raceme-like panicle which overtops the leaves.The abundant lemma hairs glisten in the sun and the shining inflorescences make the plants conspicuous when in flower.The spikelets of both species are similar in structure and appearance, differing mainly in size and in location of the hairs on the lemmas.They are awnless, somewhat laterally compressed and nor mally bear two fertile florets, the lower larger than the upper.At the end of the rhachilla is a knob-like body composed of two or three small empty lemmas which are closely rolled into each other.This clavate structure is an important character for distinguishing the genus.The glumes are boat-shaped, glabrous, and papery in texture, with raised nerves.They are about the same length as the spikelet, being sometimes slightly shorter and sometimes slightly longer.The lemmas are firmer than the paleas, with more nerves, and provide the main distinguishing character between the southern African species.In M. racemosa the hairs arise only from the lateral nerves, leaving the back of the lemma glabrous, whereas in M. decumbens there are hairs on and between the nerves over the entire lemma.The paleas are sharply folded back along the two nerves, so that the margin of the palea outside the nerve is pressed against the back of the palea, and clasps the immature anthers and stigmas.
The lower floret is always hermaphrodite, but the upper one may rarely be staminate, especially under adverse growing conditions.Melica is protandrous, and the anthers are usually shed, leaving the filaments behind, before the stigmas are exserted.The lodicules are short, thick and rounded.When the fruit is mature the florets dis-articulate at the base, and the portion of the rhacilla that bore the floret above remains pressed against the palea.The glumes are deciduous with the florets, an unusual condition in a festucoid grass.The entire spikelet may act in wind dispersal of the seed, with the lemma hairs catching the air currents as a sail.

LEAF BLADE ANATOMY
The Pooideae can be briefly diagnosed, on the basis of leaf anatomy, as follows: micro-hairs absent; silica bodies horizontally elongated square to oblong, usually with crenate or sinuous outlines; stomatal subsidiary cells parallel-sided; intercostal long cell walls often straight and not sinuous; papillae very rare; double bundle sheaths around first order vascular bundles; chlorenchyma cells not radiately arranged around the vascular bundles; bulliform cells not associated with colourless cells to form deeply penetrating fans; all vascular bundles accompanied by sclerenchyma; lateral cell count greater than four (Hattersley & Watson, 1975); non-Kranz leaf anatomy and C3 photosynthesis.M. racemosa occurs from the south-western Cape to Natal, Lesotho and the southern and eastern Orange Free State, and is rare in the eastern Transvaal (Fig. 5).It often grows among rocks on steep hill and mountain slopes and also in savanna and fynbos, at the edges of bushclumps and in grassland, and rarely between seaside dunes and in forest clearings.M. racemosa is a very variable species that includes entities described as separate species in the past.Characters used to separate these taxa such as culm length, leaf length, degree of expansion and vesture, spikelet length, glume shape and length, and number of bisexual florets vary independently and are not generally correlated.The reduction of bisexual florets to one appears to be related to hostile environments such as high altitudes a id sea

The leaf anatomy of
has divided Melica into subgenera and sections.Our two species both occur in subgenus Melica, M. racemosa in the section Melica and M. decumbens in the section Beckeria (Bemh.)Aschers.emend.Hempel.It is interesting to note that each of the three Linnaean species is the type of a different subgenus or section as recognized by Hempel.M. nutans is the type of subgenus Melica and section Melica, M. ciliata is the type of subgenus Melica and section Beckeria, and M. altissima is the type of subgenus Altimelica.Melica is thus one of the few Linnaean grass genera that has remained undivided to the present day.'Botanical Research Institute, Department of Agriculture and Fisheries, Private Bag X101, Pretoria, 0001.POSITION OF MELICA IN THE POACEAE There has been little controversy about the subfamily and tribal affinities of Melica.The genus has appeared for the past century in relatively the same position in most treatments, although the classification of the Poaceae has been changed drastically during that time.Bentham in Genera Plantarum (1883) classified Melica in series B Poaceae, tribus XI Festuceae, subtribus 6 Meliceae, along with the other genera Heterachne, Anthochloa, and Diarrhena.Modern systems, with more subfamilies, recognize the same affinities for Melica.Gould (1968), writing for North America, classified Melica in subfamily I Festucoideae, tribe 4 Meliceae, and included the genera Glyceria, Catabrosia, Pleuropogon and Schizachne.Tzvlev (1968) has classified the grasses of the USSR, with Melica in subfamily 2 Pooideae, tribe 15 Meliceae, with the genera Schizachne and Pleuropogon.For Africa, Clayton (1970) in the Flora of Tropical East Africa placed tribe XII Meliceae, in the Pooid subfamily, with only one genus from tropical Africa, Streblochaete.In an unpublished list of world grass genera (Clayton, 1980), he included six genera in the tribe, Streblochaete, Lycochloa, Schizachne, Triniochloa, Anthochloa and Melica, but placed Diarrhena, Glyceria and Pleuropogon in separate tribes.The only modern system in which Meliceae has been placed outside the Pooideae or Festuceae is that of