Mimosa sprengelii

  • Title

    Mimosa sprengelii

  • Authors

    Rupert C. Barneby

  • Scientific Name

    Mimosa sprengelii DC.

  • Description

    377. Mimosa sprengelii DeCandolle, Prodr. 2: 430. 1825, a substitute for M. ciliata K. Sprengel, Syst. veg. 2:205.1825, nom. illeg.—"Monte Video [Uruguay], Sello."—Neotypus, Sello s.n., manu Benthamii annotatus, K (hb. Benth.)! = NY Neg. 12311.— Non M. ciliata Willd., 1809.

    M. sprengelii sensu Bentham, 1841: 385; Malme, 1931: 11; Lombardo, 1964: 61, fig. 47.

    M. ciliata sensu Bentham, 1875: 409; 1876: 347; Glaziou, 1906: 180, ex parte (19133), caetera (19134, quae = M. ramulosa) exclusa.

    Erect, intricately stiffly branched microphyllous shrubs attaining 2 m, armed on most internodes with l(-3) straight, erect or subacroscopic, broad-based lustrous aculei 1.5-5 mm, the stems and short peduncles minutely puberulent and coarsely retrostrigose with appressed tapering, basally spurred setae ±0.6-1.5 mm, the lf-axes similarly but antrorsely strigulose, the small imbricate, facially glabrous lfts finely continuously callous-marginate and usually remotely minutely setose-ciliolate, the globose capitula solitary in lf-axils on short or obsolete peduncle, only in praefloration shortly pseudoracemose. Stipules firm erect, triangular or lanceolate 1.2-2.5 x 0.4-0.8 mm, pallidly 3-nerved dorsally, persistent. Leaf-stalks including small livid pulvinus 0.7-2 mm; pinnae 1-jug., the rachis 1.5— 10(—11) mm, the interfoliolar segments 0.2-1.1 mm; lfts 6-11- jug., decrescent proximally and less so distally, the small first pair ±0.2 mm distant from minute paraphyllidia, the blades narrowly obliquely ovate or lance- or linear-elliptic from shallowly semicordate base, obtuse or deltately subacute, those at mid-rachis 1-6 x 0.5-1.5 mm, 2.5-4.2 times as long as wide, all ventrally concave veinless, dorsally 2-nerved from pulvinule, the pallid midrib displaced to divide blade 1:1.5-2.5, the posterior nerve expiring well beyond midrib; terminal lfts often falcately retro-arcuate. Peduncles 1.5-5 mm, sometimes at early anthesis imperceptible; capitula without filaments 3-5 mm diam., prior to anthesis moriform, the fl-buds microscopically papillose-puberulent; bracts lance-acuminate or oblanceolate 0.6-1.5 mm, persistent; flowers 4-merous 4-androus; calyx a minute glabrous collar 0.15 mm or less; corolla narrowly funnelform 1.5-2.2 mm, the cymbiform, obtusely carinate lobes 0.6-0.8 x 0.4-0.7 mm; filaments pink or lilac, free to base, exserted 2-4 mm. Pods several per capitulum, sessile, bur-like, in profile narrowly oblong-elliptic straight 14-24 x 4.5-6 mm, to 8-seeded, the straight replum 1-1.4 mm wide, the stiffly papery valves convex, the cavity interrupted between seeds by narrow filamentous septa, the replum and valves alike densely hispid with stout erect broad-based glabrous setae 2-3 mm, the ripe valves separating entire from replum; seeds (few seen) plumply lentiform ±4x3x2 mm, the testa dull dark brown.

    On open stony hillsides, at elevations not recorded, known only from Uruguay. Records from tropical southeastern Brazil (Glaziou, 1906, l.c., discussed below) are based on faulty data.—Fl. VI, XI-I(-?), the full cycle not known.

    At anthesis M. sprengelii resembles M. ramulosa in most respects, but differs in the subsessile or very shortly pedunculate capitula. Care must be taken to distinguish true peduncles from occasional axillary branchlets which may lose their leaves at the fruiting stage and simulate elongate peduncles. The fruit of M. sprengelii appears different from that of all other Obstrigosae in valvate dehiscence and coarse hispid indumentum of the pod-valves.

    The type of Kurt Sprengel’s Mimosa ciliata has not been located, and was perhaps lost at Berlin, where much of his herbarium was housed. A Sello specimen emphatically annotated by Bentham (in his own herbarium at Kew) is proposed as neotype in the nomenclatural paragraph above. This plant agrees well with the protologue, except that it has slightly more numerous leaflets, but it cannot be known for certain whether it is in fact an isotype or part of a second collection of the species.

    Two specimens were cited and distributed by Glaziou as M. ciliata: his 19134, vaguely indicated as from the state of S. Paulo, Brazil, which is misidentified M. ramulosa (q.v.), and his 19133, which is correctly identified but was supposedly collected on Alto Macahe in Serra dos Orgãos in Rio de Janeiro. Wurdack (Taxon 19: 911. 1970) has demonstrated that two Melastomataceae labelled by Glaziou as coming from Alto Macahé were in fact collected elsewhere by Puiggari and De Moura, and has raised suspicions of deliberate fraud on Glaziou’s part. A strange detail of Glaziou 19133 (P!) is that the specimen is accompanied by a typical field-label in Glaziou’s hand, dated 8 August 1888, and a ticket bearing the same number 19133 is attached to the plant. Thus all data seem coherent and authentic. Two alternative explanations are possible: a) there really is (or was) a disjunct population of M. sprengelii, otherwise collected only in Uruguay, or of a cryptically similar relative, on the summit ridge of Alto Macahé; or b) the record was deliberately falsified. The probability that a local Uruguayan species occurs disjunctly on the Organ Mountains is low, but the truth of the matter can only be ascertained by careful fieldwork. The idea that Glaziou obtained the specimens from a correspondent and manufactured a false statement of provenance seems preposterous, but Glaziou’s field-note of fleurs jaunes, which would be an anomaly in ser. Obstrigosae, also requires explanation or confirmation. For the present it seems best to consider M. sprengelii endemic to Uruguay.