Tropicos | Name - Micranthus alopecuroides (L.) Eckl.

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Iridaceae in sub-Saharan Africa

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Micranthus alopecuroides (L.) Eckl.

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Project Name Data (Last Modified On 6/6/2016)

Acceptance : Accepted

Taxon Profile (Last Modified On 6/13/2016)

Description: Plants mostly 200–450 mm high, base usually sheathed with collar of short fibres. Corm mostly 10–12 mm diam., tunics of dark brown, relatively coarse, reticulate fibres, drawn into short bristles above. Stem usually simple or 1- or 2(3)-branched, when unbranched often with one or more scales below base of spike; usually bearing 1 or more cormlets in axil of lowermost foliage leaf. Leaves 2–4(5), lowermost 1 or 2 plane, broadly to narrowly falcate (occasionally ± lanceolate) or linear, (2–)5–10(–15) mm wide, with moderately prominent main vein; margins slightly or occasionally heavily thickened (De Vos 2288), hyaline when dry; upper 1 or 2(3) leaves largely sheathing. Spike mostly 40–80-flowered, often much congested, with internodes 1.5–3.0 mm long; bracts 5–7 mm long, outer with broad to narrow brown centre and translucent membranous margins, inner ± as long as outer, notched apically, translucent with 2 dark veins slightly broader toward base; lower or all nodes sometimes vegetative and then bracts paler in colour and subtending one (or more) cormlets in each axil. Flowers usually dark blue, sometimes pale blue, often lower third to fourth of tepals paler blue or white, distally edged with a thin darker blue line, unscented; perianth tube ± 5 mm long; tepals subequal, elliptic, 7–8 × ± 3 mm, with short narrow, claw-like base. Stamens with filaments ± 5 mm long, diverging in upper half; anthers oblong, 3–4 mm long, pale mauve; pollen white to pale blue. Style ± 7 mm long, mostly dividing between upper third of filaments and lower third of anthers; branches ± 1.2–1.6 mm long, divided for ± half their length. Capsules oblong to narrowly ovoid, ± 5 mm long but ± 4 mm long when dry. Seeds angular-elongate, 3.5–4.0 mm long, 3 or 4 per locule. Flowering time: October in the north, November to December in the south.

Country: South Africa

South African Province: Western Cape

Distribution and ecology: centred in the southwestern Western Cape, Micranthus alopecuroides has a relatively narrow range, extending from the Cape Peninsula north into the Olifants River Valley and east locally to Hermanus and Swellendam. Plants typically grow on well-drained clay or loamy, seasonally wet, slopes and flats but have also been recorded on sandy ground. The Olifants River Valley populations grow in thin clay or sandy gravel, often over rocky pavement that is totally dry even before flowering commences.

Diagnosis: Micranthus alopecuroides is distinctive in its plane, sometimes very broad basal leaves, the blades lanceolate to linear or falcate, sometimes up to 12 mm wide or exceptionally to 15 mm in plants from the Roman’s River area of the upper Breede River Valley. Exceptions are numerous and there are collections with ± linear leaves 3–5 mm wide and only up to 25 mm long (notably Purcell s.n., NBG). The flowers are typical of the genus, usually dark blue, with a perianth tube ± 5 mm long. The spikes of 40 or more flowers are often unusually congested with the internodes ± 1.5 mm long.

Populations from the Olifants River Valley and flowering in October, at least three weeks earlier than elsewhere, stand out in their relatively lax spikes with internodes 2.5–3.0 mm long (vs ± 1.5–2.0 mm elsewhere) and relatively short, straight leaves, 5–8 mm wide with particularly prominent mucronate tips. The outer bracts of these plants also differ from those in populations to the south in their broader translucent margins, thus with a significantly narrower central band of green tissue (brown when dry). These plants are typically restricted to thin clay or light sandy soils over rocky pavement and represent a distinctive race of the species

General Notes: certain collections from sandy flats south of Malmesbury constitute a puzzle. They consist of plants with abnormally elongated spikes up to 120 mm long, more than 3/4 of their length bearing small, pale bracts each enclosing not a flower but a small cormlet. Only the top fourth of the spikes have properly formed, dark brown bracts subtending either pale blue flowers (e.g. Goldblatt & Manning 10431, MO, NBG, with tubular leaves) or deep blue flowers (Goldblatt & Manning 10432, MO, NBG, with plane leaves). The leaves, either tubular or plane with a central vein, correspond to Micranthus tubulosus or M. alopecuroides respectively. We conclude that these plants constitute hybrids or a hybrid swarm with M. alopecuroides as one parent and M. tubulosus or possibly M. plantagineus as the other. Microscopic examination of the pollen shows some apparently normal grains and others smaller than normal and evidently sterile. The available collections of this putative hybrid were made too early in the life cycle to have capsules, which if developed, would have appeared later in the season.

Similar specimens from other sites show the same striking feature (e.g. Goldblatt 8711 MO, from Greyton; Leighton 722 BOL from Camp Ground, Rondebosch; and Williams 1195 MO, NBG) from near Vogelgat, Hermanus. This last collection consists of plants with the sterile part of the spikes 180–250 mm long and the fertile part 20–30 mm long. Populations at Elandsberg near Bo-Hermon, with plane, narrowly lanceolate leaves (e.g. Goldblatt & Manning 13616) have the inflorescence sterile throughout and bearing a cormlet in all bract axils as do many individuals of the species from Rondebosch Common, Cape Town (Goldblatt & Manning 13619). The status of these plants is uncertain but we suspect them to have a hybrid origin.

Note 1. Daniel Solander, the unacknowledged author of Hortus kewensis published under William Aiton’s name (1789), described the new species Ixia plantaginea ‘foliis linearibus strictis, spica disticha imbricata’, based on a collection of Francis Masson and, for reasons that are obscure, at the same time cited Linnaeus’s Gladiolus alopecuroides in synonymy. The epithet plantaginea, alluding to the similarity of the inflorescence to that of Plantago L., is no more apt than Linnaeus’s recalling the resemblance to the grass, Alopecurus L., and constitutes an illegitimate superfluous name. Nevertheless, the broad-leaved species remained known by the later epithet plantagineus, until well into the 20th century (e.g. Lewis 1950) despite the leaves being described as narrow and linear in the protologue. The epithet plantagineus was applied to M. alopecuroides by among others Ker Gawler (1803), who evidently did not realize it applied to two different species. Baker (1892, 1896), who also used the name M. plantagineus for M. alopecuroides, compounded this error and recognized M. plantagineus var. junceus not realizing that the type of the species was in fact identical with his new variety.

Note 2. Described in 1756 by Linnaeus as Gladiolus alopecuroides, with the brief diagnosis ‘foliis linearibus, spica disticha imbricata,’ the species was transferred to Micranthus by Ecklon (1827), when he raised Persoon’s Gladiolus subg. Micranthus to generic rank. Of the three sheets identified as G. alopecuroides in the Linnaean herbarium, one [LINN 59.13] is a Sparrman collection post-dating the protologue, and the other two cannot be unambiguously related to the name. One [LINN 59.15] is M. tubulosus and the other [LINN 59.14] may be M. alopecuroides but is atypical in its large size, numerous branches and particularly broad leaves that hardly accord with the protologue [leaves linear]. We prefer to choose a neotype: Barker 3384, which has relatively narrow leaves and conforms exactly to the protologue. This action unambiguously preserves the current application of the name to the plane-leaved species (Lewis 1950; Goldblatt & Manning 2000).

Note 3. Gladiolus minutiflorus Schrank (1822) has been associated with Micranthus alopecuroides, which Schrank also recognized (as Gladiolus), but the description is vague (flowers small, secund, tepals subequal) and we are unable to determine the plant to genus with confidence, let alone to species. Schrank did, however, explicitly describe the leaves as short, striate and narrow, the lower ± 5 inches (125 mm) long. No authentic material has been located either at the Munich (M) or Brussels (BR) Herbarium, the institutions where the types of Schrank’s species, when they exist, are believed to be located.