Marina diffusa (Moric.) Barneby
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Authors
Rupert C. Barneby
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Authority
Barneby, Rupert C. 1977. Daleae Imagines, an illustrated revision of Errazurizia Philippi, Psorothamnus Rydberg, Marine Liebmann, and Dalea Lucanus emen. Barneby, including all species of Leguminosae tribe Amorpheae Borissova ever referred to Dalea. Mem. New York Bot. Gard. 27: 1-892.
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Family
Fabaceae
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Scientific Name
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Description
Species Description - Glabrous shrubs up to 1-2.5 m tall, sometimes precociously flowering as suffrutescent herbs, with 1-several stiff or flexuous and wandlike, livid-purple, usually glaucescent, ligneous main stems effusely and repeatedly branching distally into a broadly round-headed panicle of slender, finally capillary branchlets, these usually stramineous, the stems only sparsely, often obscurely impressed-glandular, not tuberculate, the foliage bicolored, the leaflets green above, pallid and minutely or subobsoletely punctate beneath, lineolate both sides, the margins gland-crenulate; leaf-spurs 0.2-0.8 mm long; stipules membranous, ovate- or subulate-attenuate, 0.3-1.4 mm long, often fimbriolate at base; intra- and post-petiolular glands small but prominent, subulate or prickle-shaped; main cauline leaves (drought-deciduous, often absent from flowering specimens) 1.5-3.5 (4) cm long, with narrowly winged rachis (ventral face 0.25 -0.35 mm wide) and 6-12 (17) pairs of oblong or oblong-oblanceolate, flat, dorsally carinate leaflets 3-6.5 (7.5) mm long, the leaves opposed to and between peduncles much smaller, 1-9 mm long, 1-7-foliolate, the leaflets mostly obovate to broadly oblanceolate and entire, 0.7-5 mm long; peduncles very slender or capillary, leaf- opposed and terminal to all ultimate branchlets, 0.5-3 (4) cm long; racemes very loosely or remotely 1-25-flowered, the lowest of each primary division of the panicle 5-25-flowered (some always over 5-flowered) the terminal ones mostly 1-6-flow- ered, the axis becoming (0) 1-45 mm long; bracts enclosing the very young buds, early thrown off, obovate-cuneate, submembranous, gland-denticulate at apex, up to 1 mm long; pedicels (0.6) 0.8-1.5 mm long, charged near apex with 2 gland-grains; calyx 2.5-3.6 mm long, prominently ribbed but not pleated, the tube (1.5) 1.8-2.2 mm long, its membranous intervals charged with 1 row of (2) 3-5, distinct or irregularly confluent, orange blister-glands, the teeth ± unequal, the dorsal one longest, ovate-triangular, usually acute, 0.7-1.6 mm long, the ventral pair shortest, nearly half-circular, obtuse, 0.4-0.9 mm long, all imbricated at base, the margins pallidly membranous, erose or minutely fimbriolate, charged at apex and often laterally with 1-3 minute orange glands; petals =b bicolored, the blade of banner whitish beyond the purple-tipped lobes, the white area sometimes boldly striped, rubescent in age, the inner ones rose- or magenta-purple or deep maroon-violet, perched 1.4-3 mm above hypanthium rim, their blades sparsely gland-sprinkled; banner 2.5-3.5 mm long, the ± laterally winged claw thickened upward, 0.8-2.1 mm, the blade abruptly recurved through nearly 90°, ovate-deltate, emarginate, closed across the top of claw to form a recessed cornet, the apex sometimes gland-tipped; wings 3.5-4.7 mm long, the claw 0.2-0.4 mm, the obovate blade 3.5-4.6 mm long, 2.2-3 mm wide; keel 4.4-5.9 mm long, the claws 0.7-1.2 mm, the broadly obovate blades 4.2-5.3 mm long, 2.8—3.5 mm wide; androecium 10-merous, (5.5) 6-8 mm long, the longest filaments free for 1.5-2.1 mm, the connective gland-tipped, the pale bluish anthers 0.5-0.7 mm long; pod plumply obovoid, 2.7-2.9 mm long, 2-2.5 mm diam, little compressed, the short style-base becoming lateral or latero-subterminal, the ventral suture strongly keeled above the pore, the dorsal suture smoothly rounded and not carinate, the valves contracted proximally into a subhyaline, obconic base ± 0.3 mm long, thence firm, closely investing the seed, green or purplish becoming brown, charged with many small, low-protuberant glands ±0.2 mm diam, these arranged in no obvious pattern; seed ± 2.1-2.5 mm long.
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Discussion
(Plate XXIV)
While M. diffusa is related to M. nutans and in herbaria often confused with it, it appears in the field as an entirely different plant with a characteristic individual facies. The mature plant, veteran of several seasons’ growth, consists of two or more erect ligneous trunks up to 1-1.5 cm diameter, each of which gives rise, during the rainy summer months, to a cluster of firmly pliant, purple-glaucescent secondary stems reaching at least a meter high and densely clothed with long leaves composed of many leaflets. As the dry season approaches, the foliage begins to fall from these secondary stems which go out in turn into an airy panicle of repeatedly forking, very slender and ultimately threadlike branchlets subtended by abruptly simpler leaves mostly much shorter than the internodes, and a multitude of laxly few-flowered racemes. At full anthesis and in fruit the plant forms a broadheaded tangle of capillary branchlets, the whole bending and swaying gracefully in the least current of air, and elevated on an apparently almost leafless framework. As already mentioned under M. nutans, the flowers of M. diffusa are of fleeting duration, the petals falling a few hours after expanding, so that one rarely finds two open at once on the same raceme. The shrubs of M. diffusa are usually colonial, sometimes forming a long line along fences of cultivated land, sometimes small thickets, or more scattered populations mixed with other shrubs as an understory in oak woods.
Over much of its range M. diffusa varies little, some plants from points as far apart as Sonora and Guerrero being virtually indistinguishable. Only in a small tract of country near the middle of its area of dispersal has it developed a marked variant, here described as var. radiolata, which replaces var. diffusa locally in the canyons of the Rio Grande system in s. Zacatecas, eastern Nayarit, and adjoining Jalisco, and in the basin of Lago Magdalena in the latter state. The populations of M. diffusa in Sierra Madre del Sur and in Guatemala are only poorly collected and indifferently understood; they may conceal, as mentioned further under var. diffusa, taxonomically separable entities.