Mimosa
Sp. Pl. 1: 516. 1753.
Herbs, perennial, shrubs, or subshrubs [trees], armed or unarmed. Stems erect, scandent, decumbent, prostrate, or sprawling, terete, striate, or ribbed, prickles infrastipular, irregular in internodes, or along ribs; short shoots (brachyblasts) sometimes present, glabrous or pubescent. Leaves alternate, usually even-bipinnate, rarely some leaves unipinnate (M. borealis, M. turneri); stipules present; petiolate, petiole eglandular [glandular]; pinnae [0 or]1–14[–33] pairs; leaflets 1–40[–95] pairs, opposite, blade margins entire, surfaces glabrous or pubescent. Peduncles unarmed or prickly. Inflorescences 5–180-flowered, usually axillary, sometimes also terminal, capitula, spikes, or racemes; bracts present. Flowers mimosoid, bisexual, or staminate present at base of inflorescence; calyx campanulate, lobes 4 or 5(or 6), valvate; corolla white, pink, purple, or purple-pink, lobes 4 or 5(or 6), valvate; stamens 8 or 10 (2 times corolla lobes) or 4[5] (as many as corolla lobes), distinct or connate at bases, exserted, white, pink or lilac; anthers dorsifixed, introrse, eglandular; ovary sessile or stipitate; style longer than stamens; stigma poriform, cupuliform, or tubular [obliquely funnelform]. Fruits legumes, sessile or stipitate, straight or curved, constricted or not between seeds, linear, oblong, or tetragonal [elliptic], dehiscent, craspedial, glabrous or pubescent, valves segmented with 1 seed each or entire, usually wider than margin, persistent margin usually narrow, sometimes as wide as or wider than valves, prickly or unarmed. Seeds 1–18, ± isodiametric, lenticular, elliptic, oblong, or rhomboid, testa smooth or porous. x = 13.
Distribution
United States, Mexico, West Indies, Central America, South America, Asia, Africa, Indian Ocean Islands (Madagascar), Australia, arid or semiarid areas, tropics, subtropics, temperate regions.
Discussion
Species ca. 530 (20 in the flora).
Mimosa is divided into five sections: sect. Batocaulon de Candolle, sect. Habbasia de Candolle, and sect. Mimosa are represented in the United States; sects. Calothamnos Barneby and Mimadenia Barneby are not found in the flora area.
Mimosa diplotricha C. Wright ex Sauvalle, M. pigra, and M. pudica Linnaeus are pantropical weeds. Mimosa diplotricha and M. pigra are noxious weeds, mainly in Australia: the former is found in Hawaii and Puerto Rico but not in the continental United States. Mimosa pigra is a noxious weed and a prohibited aquatic plant in the flora. Mimosa pudica is cultivated in the United States as an ornamental and is also used for experimental projects due to its sensitive leaves; furthermore, it can be considered as introduced in the flora of Florida and Maryland. Other species of Mimosa are widely used as melliferous and medicinal plants, forage for goats, living fences, firewood sources, and for reforestation by rural communities in arid, semiarid, and tropical regions.
Selected References
None.
Lower Taxa
Key
| 1 | Inflorescences spikes. | > 2 |
| 2 | Leaves with (1 or)2–4 pinna pairs, 2–4(or 5) leaflet pairs; corollas glabrous; legumes glabrous. | Mimosa distachya |
| 2 | Leaves with 5–11 pinna pairs, 6–14 leaflet pairs; corollas densely sericeous; legumes tomentose. | Mimosa dysocarpa |
| 1 | Inflorescences capitula. | > 3 |
| 3 | Legumes segmented, each with 1 seed. | > 4 |
| 4 | Corolla lobes 4, stamens 4; legumes 3–4 mm wide; leaves with 1 or 2 pairs of digitate pinnae. | Mimosa pudica |
| 4 | Corolla lobes 4 or 5, stamens 8 or 10; legumes 5–13 mm wide; leaves with 1–14 pairs of non-digitate pinnae. | > 5 |
| 5 | Subshrubs, scandent; stems ribbed, prickles along ribs. | Mimosa malacophylla |
| 5 | Herbs or shrubs, erect or procumbent; stems not ribbed, prickles infrastipular or irregular along internodes. | > 6 |
| 6 | Corollas glabrous; legumes glabrous. | > 7 |
| 7 | Corolla lobes 2/3 corolla length; legumes oblong. | Mimosa borealis |
| 7 | Corolla lobes 1/3–1/2 corolla length; legumes linear. | Mimosa turneri |
| 6 | Corollas usually tomentose or strigose, rarely glabrous; legumes tomentose, setose, strigose, strigulose, or puberulent. | > 8 |
| 8 | Corollas tomentose; legumes tomentose and setose; stems tomentose or glabrescent, brachyblasts present. | Mimosa emoryana |
| 8 | Corollas strigose or glabrous; legumes setose or strigose to strigulose; stems strigose to strigulose or puberulent, brachyblasts absent. | > 9 |
| 9 | Shrubs, erect, 1–3 m; legumes oblong, segments (4–)7–25. | Mimosa pigra |
| 9 | Herbs, procumbent, 0.1–0.5 m; legumes obliquely oblong, segments 1–4. | Mimosa strigillosa |
| 3 | Legumes not segmented, valves entire. | > 10 |
| 10 | Shrubs; prickles infrastipular. | > 11 |
| 11 | Legumes linear, 3–4 mm wide; corollas tomentose or tomentulose. | Mimosa biuncifera |
| 11 | Legumes oblong, 5–8 mm wide; corollas glabrous or puberulent, or pilosulous on lobes. | > 12 |
| 12 | Prickles in groups of 3, 2 straight, 1 recurved; capitula 13–20 mm diam., 50–120-flowered; corollas pilosulous on lobes or glabrous. | Mimosa grahamii |
| 12 | Prickles usually solitary, rarely 2 or 3, recurved; capitula 8–15 mm diam.,. 10–30-flowered; corollas glabrous or puberulent | Mimosa texana |
| 10 | Herbs or subshrubs; prickles along stem ribs, rarely unarmed. | > 13 |
| 13 | Leaflet blades with reticulate veins prominent on both surfaces, or at least abaxially. | > 14 |
| 14 | Inflorescences axillary capitula; legumes linear-oblong, valves 3–6 mm wide. | Mimosa hystricina |
| 14 | Inflorescences axillary capitula, sometimes also terminal racemes; legumes linear, valves 1–2.5 mm wide. | > 15 |
| 15 | Inflorescences 20–30 mm diam., 90–140-flowered; peduncles 3.5–. | > 9 |
| 9 | 5 cm; racemes 130–200 mm; stipules 4.5–8 mm. | Mimosa nuttallii |
| 15 | Inflorescences 15–18 mm diam., 30–50-flowered; peduncles 0.6–1.5 cm; racemes 40–50 mm; stipules 1–2.5 mm. | Mimosa quadrivalvis |
| 13 | Leaflet blades with 1 vein slightly evident only on abaxial surface. | > 16 |
| 16 | Petioles shorter than primary rachis; pinnae (3 or)4–9 pairs; legumes linear, to 140 mm. | > 17 |
| 17 | Leaflet blades obliquely linear, 0.5–1 mm wide, surfaces not glaucous; capitula 60–120-flowered, bracts linear, 1/3–1/2 corolla length; legumes. | > 1 |
| 1 | 5–4 mm wide, sessile. | Mimosa microphylla |
| 17 | Leaflet blades obliquely linear-oblong to oblong, 1–1.5 mm wide, surfaces glaucous; capitula 30–60-flowered, bracts spatulate, 1/4–1/3 corolla length; legumes 3–5 mm wide, stipitate. | Mimosa rupertiana |
| 16 | Petioles as long or longer than primary rachis; pinnae 1–3 or 2–5 pairs; legumes linear-oblong, to 90(–100) mm. | > 18 |
| 18 | Pinnae 2–5 pairs; capitula 100–180-flowered; legume valves slightly wider than margin. | Mimosa roemeriana |
| 18 | Pinnae 1–3 pairs; capitula 20–70-flowered; legume valves narrower than margin. | > 19 |
| 19 | Leaflets 6–9 pairs, blades obliquely linear-oblong to oblong; corolla lobes 1/2 corolla length; legumes 25–60 × 2.5–4 mm. | Mimosa latidens |
| 19 | Leaflets 9–14 pairs, blades obliquely linear; corolla lobes 1/4–1/3 corolla length; legumes (45–)70–90(–100) × 4–4.5(–5) mm. | Mimosa monclovensis |