Dedeckera Eurekensis Reveal & Howell, Sp
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246 BRITTONIA [VOL. 2 8 Dedeckera eurekensis Reveal & Howell, sp. nov. (Fig. 1) Frutex 0.2-0.7 m altus, 0.5-2 m latus; caules foliosi, hirsutuli; folia alterna petiolata exstipulata, laminis ellipticis hirsutulis, 1-1.5 cm longis, (4-) 5-7 mm latis; inflorescentiae cymosae, 1-3 (-4) cm longae; pedunculi erecti; involucra nulla; flores lutescentes 1.8-3 mm longi, hispiduli; achaenia 2-2.5 mm longa. Large, densely branched shrubs 0.2-0.7 m tall, 0.5-2 m across, with numerous, gray, woody branches arising from a stout, woody root, the woody branches spread- ing, covered with thin, grayish bark, the bark becoming thicker and slightly reticulate near the base of the larger and more woody individuals, a single stem up to 3 cm across at the base, the upper herbaceous growth annually produced from the axils of the uppermost leaves of the previous year's growth, these branches thin and, with age and time, often becoming rigid and somewhat spinose; leaves alternate, green to yellowish-green, hirsutulous, the leaf-blade elliptic, 1-1.5 cm long, (4-) 5-7 mm wide, thin pubescent on both surfaces, the hairs slightly more dense and longer on the margin, the margin entire and plane, the apex acute to narrowly obtuse, the base tapering gradually to the 2-5 mm long petiole, the petiole greenish to whitish- yellow or tannish depending upon age, with the pubescence more pronounced along the margin, the petiole-base tannish to whitish-yellow, elongate-triangular,0.8-1 mm long and wide, pubescent on both surfaces; flowering branches annually produced, greenish, erect or nearly so, leafy, 2-7 (-10) cm long, hirsutulous throughout with short, spreading hairs, the stems often becoming tannish with age especially among the leaves; inflorescences cymose, 1-3 (-4) cm long, mostly trichotomously branched, divided 1 to 4 times, the green hirsutulous branches becoming reduced in length upwardly, with a single, short-pedicellate flower and a single peduncle at each node; bracts of the inflorescence foliaceous and similar to the leaves except reduced in size toward the apex, the 3-4 bracts of the lowermost node up to 1.2 cm long, the 2-3 bracts of the upper nodes much reduced and somewhat scale-like, always less than half the length of the lower ones; peduncles erect, slender, greenish, the lower one 4-6 mm long, the upper ones greatly reduced, with the ultimate branching consisting only of short, but in fruit elongating to 1.5 mm, peduncles; floral bracts lanceolate to broadly lanceolate, 1-2 mm long, 0.4-0.6 mm wide, the 5 bracts common on all peduncles except the uppermost which have 3, or rarely 2, greenish but drying tannish, arranged in 2 whorls, with the outer whorl of 3 broader and longer than the inner whorl of 2, the inner 2 sometimes very small, or one larger than the other, becoming lost in the uppermost parts of the inflorescence, the minute pedicels of the clustered, upper inflorescences peg-like, rarely more than 0.5 mm long, and then only the outermost whorl of flowers on these projections; bractlets minute, those of the lower 5-bracted peduncles in 2 whorls, the outer ones lanceolate, 0.5-1 mm long, with the outer surface pubescent and the inner surface glabrous, the inner ones narrowly elliptic, 0.4-0.8 mm long, minutely pubescent throughout, the bractlets of the upper 3-bracted peduncles composed of a single whorl, linear, 0.2-0.5 mm long, minutely pubescent throughout, the bractlets of the solitary, short-pedicellate flower reduced to 2, linear, tannish to reddish-brown, 0.6-0.9 mm long; flowers sessile or subsessile on peg-like pedicels in clusters of 7-10 atop the lower peduncles and 5-7 at the tips of the ultimate peduncles, the single flower at the base of the peduncle on a short, slender pedicel 0.3-1 mm long, the pedicel hispidulous, the flowers yellow in anthesis, becoming somewhat paler in color after fertilization and before darkening to a reddish-yellow in fruit, 1.8-2 mm long at anthesis, maturing 2.5-3 mm in fruit, the 6 tepals narrowly lanceolate, the 3 inner tepals slightly narrower and shorter than the outer tepals, plane and flat within, thickened and keeled along the midrib without especially in fruit, densely hispidulous without, sparsely hairy within mainly 1976] REVEAL & HOWELL: DEDECKERA 247 D~~~~~~~~~~~~ A~ FIG. 1. Illustration of Dedeckera eurekensis showing: A, the general habit of the species, X 0.1; B, a single branch, X 1; C, an enlargement of a single inflorescence illustrating the single pedicellate flower at the axes of the lower nodes, X 3; D, a single flower, X 6; and E, a mature achene, X 8. along the midrib, united about ?5 the length of the flower at the base and firmly clasping the fruit; stamens 9, the filaments attached at the base of the tepals, 1-2 mm long, yellowish, pilose basally, the inner whorl of three maturing before the outer whorl of 6, the anthers oblong, 0.2-0.3 mm long, the pollen golden-yellow; ovary green, pubescent with long, thin, curly hairs at the apex; achenes light reddish-brown, 2-2.5 mm long, triquetrous, the narrowly globose base tapering gradually to the slightly hispid apex; embryos green, curved, enclosed in dense, white endosperm. 248 BRITTONIA [VOL. 28 TYPE: UNITED STATES. CALIFORNIA. Inyo Co.: Last Chance Range, in a rocky canyon about 3 airline mi (4.8 km) SE of Eureka Valley sand dunes and 3.5 airline mi (5.6 km) NW of Marble VABM 7559, in TIOS, R40E, on steep limestone, north-facing, rocky slopes in the canyon, associated with Atriplex, Eriogonum and Prunus at about 4000 ft (1200 m) elev., 29 Jul 1975, J. L. Reveal, M. C. DeDecker & P. W. DeDecker 3909 (HOLOTYPE: US!; ISOTYPES: 35 to be distributed). Additional specimen examined: Type area, 4 Jul 1975, M. C. DeDecker 3892 (CAS, DeDecker, RSA, US). DISCUSSION Dedeckera is a member of the subfamily Eriogonoideae of Polygonaceae, and is most closely related to Eriogonum Michx., a large genus of nearly 250 species found mainly in the western United States. The new genus differs primarily from Eriogonum in lacking the distinctive tubular involucre which denotes not only Eriogonum, but other related genera as well, namely Chorizanthe R. Br. ex Benth. (which may be divided into additional genera such as Centrostegia A. Gray ex Benth. and Mucronea Benth.), and Oxytheca Nutt. It differs from the even larger series of genera which lack the tubular involucre in being a shrubby perennial, and thus Dedeckera may be quickly distinguished from Stenogonum Nutt., Nemacaulis Nutt., Hollisteria S. Wats., Gilmania Cov. and Lastarriaea Remy in Gay by this single feature alone. The two remaining genera belonging to the subfamily, Harfordia Greene & Parry and Ptero- stegia Fisch. & Meyer, are separated from the rest of the taxa by a series of bract features. Harfordia shares with Dedeckera a shrubby habit but that genus is easily distinguished by its opposite leaves, six stamens, and large, inflated fruiting bracts. The new genus may be characterized by its unusual inflorescence which consists of clusters of sessile or nearly sessile flowers atop slender, erect peduncles which have two or three spreading bracts (or five bracts at the lower nodes) and the presence of a single, short-pedicellateflower at the base of each peduncle. In addition, the cauline leaves and stems have short, spreading, shiny hairs, a pubescence type found only in a small number of species of Eriogonum (i.e., E. intrafractum Cov. & Mort., E. latens Jeps.). The flowers and fruits of Dedeckera are typically like those of Eriogonum, and the other genera related to it. It would appear that Dedeckera represents either a basic expression within sub- family Eriogonoideae that would suggest an early separation of Eriogonum and Dedeckera from a common ancestral parent, or a line of evolutionary development from those species of Eriogonum belonging to the subgenus Eucycla Nutt., and particularly from the section Corymbosa Benth. In most cases, the genera of Eriogonoideae can be traced eventually to the genus Eriogonum. However, such a relationship is difficult to establish for Chorizanthe and its associated genera, and nearly impossible for Harfordia and Pterostegia. For Oxytheca, Stenogonum, Nemacaulis and Hollisteria, all their points of origin are within the limits of the subgenus Ganysma (S. Wats.) Greene of Erio'vonum,and these points can be easily established. Chorizanthe, in North America, as well as Mucronea and Centrostegia, are strictly annual, but in South America, many of the species of Ckorizanthe are perennial herbs and shrubs. Mucronea, Centrostegia and Lastarriaea have evolved from Chorizanthe,but the question, still largely unresolved, is whether or not the early forms of Chorizanthe were annuals or perennials. It may be suggested that the earliest forms were perennial, with the perennial species being eventually eliminated in North America (perhaps through competition with the rapidly evolving annual species of Eriogonum), while in South America, where Chorizanthe has not been subjected to the competitive genus Eriogonum, the 1976] REVEAL & HOWELL: DEDECKERA 249 perennials have survived. It is possible that the earliest types of Chorizanthe evolved from a pre-Eriogonum ancestral group, with Harfordia coming out even earlier, and Dedeckera developing later than Chorizanthe. If, on the other hand, Dedeckera evolved from an existing group in Eriogonum, then one must look to the section Corymbosa, a complex group that contains E. microthecum Nutt. and E. corymbosum Benth. in DC. While no species of the section approachesD. eurekensisin terms of its pubescence type, a possible connection can be seen in the small, cymose inflorescences, leafy stems, and generally shrubby habit.