Monographs Details: Mimosa paulii Barneby
Authors:Rupert C. Barneby
Authority: Barneby, Rupert C. 1991. Sensitivae Censitae. A description of the genus Mimosa Linnaeus (Mimosaceae) in the New World. Mem. New York Bot. Gard. 65: 1-835.
Family:Mimosaceae
Scientific Name:Mimosa paulii Barneby
Synonyms:Mimosa callithrix Malme
Description:Species Description - Slender single-stemmed shrubs ±2 m with 2-3 prominently ribbed, pliantly spreading-ascending branches, either unarmed or armed on young stem and on dorsal and lateral ribs of lf-stks with scattered recurved, stramineous brown-tipped aculei 0.5-2 mm, the homotinous branchlets and foliage finely thinly silky-strigulose overall, the lfts bicolored, olivaceous above, pallid beneath, the loose fl-spikes axillary to distal lvs and shorter than them. Stipules firm, linear-attenuate subinvolute 3-11 x 0.5-0.9 mm, persistent. Leaf-formula iv-viii/(9-)l 1-16; longer lf-stks 7.5-15 cm, the petiole with pulvinus 1-3.5 cm, the longer interpinnal segments of lf-stk 1-2.8 cm, the ventral sulcus either continuous or bridged between pinna-pairs but spicules 0; pinnae distally accrescent, the rachis of longer ones 3-7.5 cm, the longer interfoliolar segments 2.7-5 mm; lfts decrescent at each end of rachis, in outline narrowly oblong from deeply semicordate base, deltately acuminulate, those near mid-rachis 7-12.5 x 2-3.7(-4.4) mm, 3-3.6 times as long as wide, all weakly 3-nerved from pulvinule, the displaced midrib dividing blade 1:2-5, the inner posterior nerve produced usually almost to blade’s apex, the outer one very short, the venation all immersed above, sometimes bluntly prominulous beneath, a faint secondary venulation sometimes perceptible. Flower-spikes without filaments 7-8 mm diam., the peduncle and axis together 4.5-9.5 cm, the linear bracts caducous, the pedicels either stout 0.25 mm or obsolete; flowers 5-merous 10-androus, mostly bisexual; calyx membranous campanulate 1.5-1.9 mm, densely silky-pilosulous, the depressed- deltate teeth ±0.4 mm; corolla turbinate-campanulate 3.1-3.5 mm, densely silky-pilosulous externally, the erect ovate 3-nerved lobes ±1.5 x 0.7 mm; filaments purple, free almost to base, exserted ± 5 mm. Pods scattered along raceme-axis, in profile narrowly linear, almost straight, long-attenuate at each end but not truly stipitate, overall 35-50 x 3 mm, 5-8-seeded, the shallowly undulate unarmed replum 0.35-0.6 mm wide, the papery valves bullately distended over each seed, the replum and valves alike densely minutely pilosulous and remotely livid-granular, the ripe valves breaking up into free-falling, ellipsoid, individually dehiscent articles 4.5-6.5 mm long, the basipetal seeds ±3 x 1.8 mm, their testa lustrous brown.

Distribution and Ecology - On banks and bed of intermittent streams in pine-forest, near 1200-1500 m, known only from canyons of ríos Fuerte and Urique on the w. slope of Sa. Madre Occidental in lat. 27°-28°N, s.-w. Chihuahua (Mojarachic, Cerocahui, Sa. Charuco).—Fl VII-IX; fr IX-?

Discussion:

Mimosa pauli has much in common with M. palmeri, but differs in habit, ecology, and in the morphological characters listed in the serial key. The new epithet refers to Paul Carpenter Standley (1884-1963), who first described the species.

Distribution:Mexico North America| Chihuahua Mexico North America|

Narratives:Mimosa pauli