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Project Name Data (Last Modified On 11/15/2012)
 

Flora Data (Last Modified On 11/15/2012)
Genus MIMOSA L.
PlaceOfPublication Sp. P1. 516. 1753.
Synonym ?Panthocarpa Raf. Neogen. 2. 1825, fide Dalla Torre & Harms. Eburnax Raf. New Fl. N. Amer. 1:42. 1836, in part. Lomoplis Raf. Sylva Tell. 118. 1838. Sensitiva Raf. loc. cit. 119. 1838. Pteromimosa Britt., in N. Am. Fl. 23:171. 1928. Neomimosa Britt. & Rose, loc. cit. 172. 1928. .Mimosopsis Britt. & Rose, loc. cit. 174. 1928. Acanthopteron Britt., loc. cit. 179. 1928. Haitimimosa Britt., loc. cit. 179. 1928.
Description Coarse herbs or shrubs (in Panama), usually sprawling, decumbent to sub- scandent, heavily or lightly armed (in all Panamanian species except sometimes M. pusilla) with recurved thorns, variously pubescent. Leaves often sensitive (re- sponding visibly to touch or other stimuli), bipinnate, the pinnae 1 to many pairs, opposite, the leaflets 2 to many pairs per pinna; petioles pulvinate, eglandular (in Panama), usually aculeate; rachis eglandular but often spinose- or subulate- appendaged; pinnae usually short, pulvinate, the pulvinus commonly setose; leaf- lets large and few or more commonly-- small and many, inequilateral basally, if pubescent usually strigose; stipules narrow, subpersistent. Inflorescence of pedunc- ulate heads (in all Panamanian species) or spikes, these axillary from lower foliate and/or subterminal non-foliate nodes-; floral bractlets usually shorter than the corolla, subpersistent. Flowers pinkish or whitish, normally sessile, small, numerous, usually perfect; calyx commonly very minute; corolla several times exceeding the calyx, usually funnelform, 3-6 (mostly 4) -lobed, the lobes equalling or shorter than the tube, valvate; stamens as many as or twice as many as the corolla lobes, free, exserted, the small anthers eglandular; ovary generally short, few- to many- ovulate, the style about equalling the stamens, the stigma not expanded. Legume linear to broadly oblong, flat, thin, with persistent margins, usually (as with all Panamanian species) transversely articulate, commonly setose-spinose.
Habit herbs shrubs
Note Primarily western hemisphere from United States to Argentina, especially abundant in tropics and subtropics; a few species are known from Africa and Asia. On the whole, the genus presents a rather natural grouping, grading, however, into certain (generally recognized) segregates such as Schrankia. Many of the species of Mimosa seem constantly distinctive, while others have evolved into a number of indistinct forms which are usually graced with (doubtfully tenable) specific names. As a result considerable condensation is in order, a common con- dition among most genera of the MIMOSOIDEAE. In addition to Bentham's original classical work on the Leguminosae, B. L. Robinson presented a "Revision of the North American and Mexican species of Mimosa" (Proc. Am. Acad. 33:305. 1898). Britton and Rose in the 'North American Flora' list about 150 species of Mimosa north of South America, of which 9 have been collected in Panama. A number of additional species are known from neighboring regions, some of which well may be collected in Panama eventually. Listed from Costa Rica are: M. albida, M. Calderoni, M. dormiens, M. flavescens, and M. Watsonii. Listed from Colombia by Britton and Killip (Ann. N. Y. Acad. Sci. 35:148-154. 1936) are: M. albida, M. Andreana, M. colombiana, M. debilis, M. dormiens-, M. esmeraldae, M. flavescens, M. floribunda, M. jiramenensis, M. Killipii, M. Lawranceana, M. leio'carpa, M. Martensis, M. oligacantha, M. polycarpa, M. quitensis, M. santanderensis, M. spiciflora, M. tenuiflora, and M. Trianae, a number of them recognized species of long standing.
Key a. Pinnae a single pair per leaf. b. Leaflets 10-40 mm. long, 4-15 mm. wide, 2-6 pairs per pinna; legume 4-12 mm. wide. c. Leaflets only 2 pairs per pinna, mostly 3-4 cm. long. d. Leaflets 10-15 mm. wide, ovate to elliptic (broadest below the middle); legume mostly 6-10 mm. wide; head more robust. e. Twigs glabrous or nearly so, copiously armed; leaflets spar- ingly if at all strigose; floral bractlets prominent, exceeding and obscuring the subglabrous buds ............................................. 1. M. VELLOZIANA ee. Twigs usually pubescent, sparingly aculeate; leaflets densely strigose; floral bractlets no longer than and scarcely visible among the puberulent buds ....................................................... 2. M. ALBIDA dd. Leaflets mostly 4-10 mm. wide, more or less obovate (broadest above the middle); legume about 4 mm. wide; head less robust.. 3. M. PANAMENSIS cc. Leaflets 3 or more pairs per pinna, mostly 1-3 cm. long .................. 4. M. CASTA bb. Leaflets 3-12 mm. long, 1-2 mm. wide, about 16 pairs per pinna; legume about 4 mm. wide ..................-.................-.......... 5. M. PUDICA aa. Pinnae 2 or more pairs per leaf, at least on some or most leaves. b. Rachis very condensed or obsolete, the pinnae thus subdigitate; sta- mens as many as the corolla lobes. c. Pinnae no more than 2 pairs; peduncle about 2 cm. long in m aturity .... ............................................................... 5. M . PUDICA cc. Pinnae 3-5 pairs; peduncles short, about 1 cm. long ...... 6. M. POLYDACTYLA bb. Rachis approximating or exceeding the petiole, the pinnae compara- tively remote and quite obviously not subdigitate; stamens twice as many as the corolla lobes. c. Slender plants, with shorter thorns and softer pubescence; leaflets with 1 main vein or costa; pinnae usually 2-5 (1-8) pairs; rachis approximating the petiole, setiform-appendaged. d. Corolla membranous, not striate; pubescence not glandular; twigs strongly angled or terete. e. Twigs terete or nearly so, scarcely if at all aculeate; pinnae 1-3 pairs; secondary veins of leaflet conspicuous; heads some- what obconic, conspicuously bracteate ......... 7. M. PUSILLA ee. Twigs strongly angled or tetragonal,, heavily aculeate; pinnae usually 4-5 pairs; secondary veins of leaflet obscure; heads nearly orbicular, inconspicuously bracteate ...............................-. 8. M. INVISA dd. Corolla striate; pubescence almost always glandular-tipped; twigs subterete ............. ...-. 9. M. SOMNIANS cc. Coarse plant, formidably armed and setose-hispid; leaflets longi- tudinally few-veined; pinnae usually at least 10 pairs; rachis much exceeding the petiole, spinose at insertion of the pinnae ..............0.... I. M. PIGRA
 
 
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