Adromischus rodinii (A. marianiae 'Kubusensis') (engl) PDF Imprimer E-mail
Adromischus - species
Écrit par P.C. Hutchison   
Lundi, 22 Décembre 2008 21:15

STUDIES IN THE CRASSULACEAE

3. Adromischus Rodinii - a New Species from Namaqualand

By P. C. HUTCHISON

University of California Botanical Garden (Berkeley) Contribution No. 131.

Publication in Cactus & Succulent Journal of America, XXV  Nr. 5   1953

[Note: Now, this plant is Adromischus marianiae 'Kubusensis']

Fig. 106. Adromischus Rodinii P. C. Hutchison. U.C.B.G. N° 50.1181, ca nat. size. Photo by author.

Adromischus Rodinii P. C. Hutchison, sp. nov. Planta succulenta perennis cauli brevi laevi contorto foliis oppositis oblanceolato-spathulatis apice aliquantullo acutis pagina superiora leviter convexis subtus rotundatis usque ad 6 cm. longis 2.2 cm. lalis viridibus margine 2 cm. ad apicem versus concolore vel porphyreo spiculis cerosis inconspicue maculatis aliquantulo curvato-adscendentibus diametro basali ovali 4 mm. eo ad apicem versus ovali vel ovato insuper leviter plano diam. ad 22 mm. Inflorescentia simplex pedunculo usque ad 30 cm. longo rachi ad 13 cm. longo floribus alternantibus singularibus erectis. Perianthi tubus glauco-viridis 12 mm. longus diam. 4 mm. medio leviter constrictus diametro valde pentagonalis limbo usque ad tubum dissecto lobis oblongo-ovatis aliquanto acutis 1.5 mm. latis 3.0 mm. longis luteo- vel viridi-albis marginibus atrorubiginosis leviter recurvatis.

Fig. 107 Adromischus Rodinii P. C. Hutchison. 1. Leaf, side view. 2. Leaf, top view and transverse sections. 3. Flower, side view. 4. Spread limb, top view. 5. Reflexed limb, top view. 6. Bud, side view. 7. Outline cross-section mid-tube. 8. Stamen insertion. 9. Carpels. 10. Nectary scale. 1, 2, nat. size; 3-9, 3 x; 10, 9 x.


Stem at first erect, later prostrate, rooting at nodes, thick, brownish, smooth, somewhat contorted. Leaves approximately opposite, somewhat curved-ascending, distinctly petioled, oblanceolate-spatulate with a rounded or somewhat acute apex, more or less convex on the upper face, strongly convex below, to 6 cm. long, 2.2 cm. wide, bright green or almost yellowish green, inconspicuously pitted with lighter flecks, apical 2 cm. concolorously or purplish brown keeled on the margins, cross-section of petiole oval and 4 mm. diam., above petiole oval to round and often less convex on upper side and up to 22 mm. diam. Inflorescence terminal, simple, the peduncle 20 to 30 cm. long, terete, 3 to 4 mm. diam., green shading to purplish brown, slightly glaucous, lower 8 to 12 cm. with 8 or more thick, blunt, deltoid, purplish, sterile bracts 1.5 mm. broad and ca. 1.0 mm. long, rachis 9 to 13 cm. long, flowers 6 to 12, alternate, erect, single. Pedicels terete, glaucous, 4 to 6 mm. long, 2 mm. diam. at base, 3 mm. diam, at middle, slightly constricted apically, subtended by a small deltoid-acuminate bract and with two smaller bracts on the lower part. Calyx lobes deltoid, acute, sometimes purplish tipped, ca. 1 mm. wide and 1.5 mm. long. Perianth tube glaucous green, 12 mm. long, 4 mm. diam., slightly constricted at the middle, cross-section strongly pentagonal with rounded corners, sinuses extending as conspicuous indentations of tube to base. Limb lobes free, slightly recurved, dextrorsely twisted apically, oblong-ovate, somewhat acute, 1.5 mm. broad, 3.0 mm. long, pale yellowish or pale greenish white with dark purplish maroon margins. Filaments biseriate at about middle of tube, 3 to 4 mm. long, pale green, anthers oblong, yellow, included. Carpels ca. 9 mm. long, green, style subulate, greenish white, stigmas unenlarged, included. Nectary scale 1 mm. long, 2 mm. broad, apex shallowly concave, sides convex, corners rounded, pale yellow.

  • South Africa: Namaqualand, near Hellsberg in the Richtersveldt, Oct. 10, 1947, R. Rodin 1617 (Univ. Calif. Bot. Gdn. No. 50.1181) (UC-Holotype).


On younger leaves the upper face is generally less convex and sometimes almost flat; the leaf apex is usually more acute and the marginal keel more distinct. Under glass the leaves tend toward laxness, and older leaves of a flowering stem, in particular, may assume a horizontal position or may droop, as may the inflorescence (cf. fig. 108).

Stellenbosch No. 6065 (U. C. Bot. Gdn. No. 51.808), collected at Helskloof by Mr. H. Herre, is undoubtedly conspecific with this new species although it differs in a number of characters. The leaves are darker green with more conspicuous grey flecks giving the plant a grey aspect. The marginal keel is less distinct and the upper leaf-surface more convex. The leaf base is thicker (5 to 6 mm. diam.) resulting in a less distinct petiole. The upper leaf-surface is apparently never flattish, even on younger leaves. One leaf developed a somewhat retuse apex.

Adromischus Rodinii is most closely allied to A. marianae v. immaculatus Uitewaal [A. marianiae 'Immaculatus'] and A. kubusensis Uitewaal [A. marianiae 'Kubusensis'] , sharing with these species, in particular, the short almost obsolescent stem, odd, somewhat clavate leaves and very thick-tissued, short-lobed flower with conspicuous indentations from the lobe sinuses to the base of the tube. Floral and leaf characters also rather closely relate A. Rodinii to A. antidorcatus Poellnitz and A. Herrei (Barker) Poellnitz.


I wish to acknowledge the preparation of the Latin diagnosis by Dr. Rimo Bacigalupi.


A. J. A. Uitewaal of Amsterdam had long cultivated Stellenbosch No. 6065 and in correspondence indicated that he considered it a new species, but he kindly deferred publication when he learned of my work on this genus and in particular on this species.
Two other Adromischus collections made by Rodin in Namaqualand have likewise proven to be new and will shortly be described in this journal. The cytology of these and other species of the genus will be reported in some detail at a later date.
This new species is dedicated to Dr. Robert J. Rodin, who as a graduate student acted as Botanist for the University of California African Expedition, 1947-1948. During his travels in South Africa he collected and sent back to this institution some hundreds of succulent plants,* either as seed or as living specimens, among over 4000 numbers of African plants. His doctoral thesis (1) and two publications (2, 3) are in large part based on his work in Africa. While attempting the determination of the Rodin collections of African succulents I became interested in the systematics of Adromischus and this in turn leas led to a successful attempt to bring together a nearly complete collection of the species, which permits the current intensive investigation of this genus.


Adromischus Rodinii has proven to be rather difficult in cultivation as are those species most closely related to it. It requires very well-drained soil and more cautious watering than most Adromischus. The leaves will not endure as intense insolation as other species which, together with its lack of leaf pigmentation, suggests that in its habitat it may grow in crevices or under shrubs where it is partially sheltered from the strong light characteristic of the Richtersveldt. The older leaves seem to be short-lived. They rarely survive more than a year on our plants. Plants grown outside in full summer sun have approximately the same morphology but the general habit and inflorescence is always much more compact. These plants like-wise have a tendency to lose their lower leaves. Propagation is best accomplished by leaf cutting with the next to the oldest leaves giving most satisfactory results. The specie will undoubtedly be of interest only to collectors specializing in rare and unusual plants, since it lacks coloring, is slow-growing, and is scarcely distinctive enough in other respects for use as a bedding plant.

REFERENCES


Rodin, R. J. "Anatomical Studies in the Foliar Organs of Welwitschia mirabilis." Ph.D. Thesis on file, Univ. Calif. Library, Berkeley, 1951, 89 pp., 84 figs.
Rodin. R. J. "Petrified Forest in South-West Africa." Jour. Paleo. 25: 18-20, 1951.
Rodin, R. J. "Distribution of Welwitschia mirabilis." Amer. Journ. Bot. 40(4): 280-285, 1953.



*An annotated list of the succulents he collected is in preparation.


Fig. 108. Adromischus Rodinii P. C. Hutchison, flowers, showing degree to which lobes spread during foggy weather. During the first two years of observation the flowers never fully opened due to foggy weather. Curvature of pedicels and angle of flower in this photo is due to lax inflorescence which developed during a foggy period under greenhouse conditions. Photo by M. Kimnach, ca. nat. size.
Fig. 109 (right). Adromischus Rodinii P. C. Hutchison. U. C. B. G. No. 50.1181. Photo by M. Kimnach, ca. 0.8 x.






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