[5. arborea (Rock) Degener & I. Degener; S. hawai- iensis Degener & I. Degener; S. hobdyi Degener & I. Degener; S. molokaiensis (Degener & Sherff) Degener & I. Degener; S. tomentosa f. arborea Rock; S. t. var. molokaiensis Degener & Sherff]
(end, V) ‘Ohai
Shrubs with decumbent or sprawling branches up to 14 m long, sometimes small erect trees 2.5-6 m tall, densely silky villous, the hairs somewhat spreading, especially on young growth, often appressed on older stems. Leaflets (12-) 18-38, oblong- elliptic to narrowly elliptic, 15-38 mm long, 5-18 mm wide, densely to sparsely silky strigose, sometimes glabrate, especially upper surface, or even glabrous, apex rounded, subtruncate, or weakly emarginate, and apiculate, base rounded to broadly cuneate, often oblique. Flowers 2-9 in racemes 1.2- 7(-11) cm long, pedicels 9-40 mm long, rachis and pedicels densely silky villous, the hairs spreading to appressed; calyx green, 12(-15) mm long, strigose to glabrous, pubescent along upper edge within, sinuses with 0-2 glandular appendages, lobes del- tate, 1.5-4 mm long; corolla salmon tinged yellow, orangish red, or scarlet, rarely pure yellow, sometimes wings and keel darker than standard, standard 23-45 mm long, strongly reflexed, center yellow or greenish yellow, claw with a pair of callosities 0.5-3 mm long, these slightly curved or bent at right angles, or sometimes absent, wings 23-45 mm long, keel slightly shorter. Pods 70-230 mm long, 4-6 mm wide, slightly flattened, often somewhat constricted between the seeds, indehiscent or very tardily dehiscent. Seeds (4-)6-27, olive to pale or dark brown, oblong-ellipsoid to oblong, 4-6mm long, 2-4 mm wide. [2n = 24*.] Formerly occurring widely in lower elevation, dry habitats on all of the main islands and at least on Necker and Nihoa of the Northwestern Hawaiian Islands, now, because of destruction of lowland habitats, restricted to relictual populations on sandy beaches, dunes, soil pockets on lava, and along pond margins (only Mana, Kaua‘i), 0-830 m, scattered throughout its former range.— Plate 95.
Sesbania tomentosa exhibits considerable morphological variation in habit and most size, color, and pubescence attributes. When populations are observed in the field, the impression is one of a series of distinctive entities. In fact, in a recent master’s thesis (Char, 1983), 7 species and a total of 9 taxa were recognized; however, Char’s morphometric analysis of many characters clearly showed that they vary independently and that the differences represent differing populational means rather than discrete quantitative or qualitative differences. The lack of any phytogeographic pattern to any of these distinctive-appearing populations is further evidence that they do not merit formal taxonomic recognition. It appears that this variation pattern is accentuated by the relictual nature of the present range of this species. Sesbania tomentosa thus represents a relict polymorphic species, similar to many other Hawaiian species, now represented by a series of populations, each of which have a more or less fixed subset of characteristics, especially habit, corolla color, and pubescence. The most distinctive population is the upland, arborescent, small-leaved f. arborea of Moloka‘i, which probably merits formal recognition. Sesbania tomentosa appears to be related to species in the South Pacific or Australia.