Sedum torulosum (engl) PDF Imprimer E-mail
Sedum - Species
Écrit par Robert T. Clausen   
Vendredi, 23 Janvier 2009 17:32

Description of a Torulose, Shrubby Sedum from Mexico


First Publication in Cactus & Succulent Journal of America, vol 18, Nr. 10, 1946, pp. 151-152.

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Sedum torulosum R. T. Clausen, sp. nov., subgeneris Pachysedum.

Suffrutex ramosus, ad 8.5 dm. altum, caule robusto, 10 cm diam ad basin; ramis 0.8-2 cm. diam., 0.8 cm. diam. sub rosellis, prominenter torulosis, robustissimis et pruinosis ad apices; folliis crassis, rhomboideo-spathulatis, maxime acutis ad apices, sessilibus, spiraliter insertis, proxime artatis ad apices ramorum, 0.5-5.2 cm. longis, 0.5-1.5 cm. latis, 1-2 mm. crassis, pruinosis in juventute; rosellis foliorum evolvantibus ex amplificatione caulis et tunc gradatim protrudentibus et gradatim crescentibus ex origine ut caulis auget; floribus in cymis terminalibus corymbiformibus, 5.5 cm. diam.; pedunculo 12 mm, longo; floribus 5-partitis, rariter 4-partitis, sessilibus vel in pedicellis robustis ad 4 mm. longis, 12-13 mm. diam., flavis; sepalis connexis ad basin, lobis divaricatis, tum reflexis et marcidis breviter post anthesem, lineari-lanceolatis, obtusis, flavidis, 3-4 mm. longis; petalis late divaricatis, elliptico-oblongis, minute apiculatis, carinatis, erosis, 5-6 mm, longis; staminibus 4-5 mm. longis; squamis oblongis, truncatis, rubris, 0.3 mm. longis; pistillis erectis, flavis primo, tum viridibus ut flores maturant, 4-5 mm. longis. Typus est C46-33 in herbario Cornell University, Ithaca, N. Y. Specimen a Mrs. Ethel Rush, Los Angeles, Calif., S. R. 18, originaliter receptum. Locus certus typi est incognitus, sed hic est in Mexico, possibiliter in Coahuila

The stout, irregularly thickened stems of Sedum torulosum are distinctive. No other species of Sedum is quite like it in this respect. The relatively thick, rhomboidally spatulate leaves are pruinose and closely crowded at the ends of the branches. Two features of the flowers seem noteworthy. The sepals, which are linear-lanceolate, are divergent and become reflexed and wither shortly after anthesis. The nectar scales, in sharp contrast with the lemon-yellow of the other floral parts, are red. S. torulosum seems to be a species of the subgenus Pachysedum, but possibly not closely related to any of the other known species. S. dendroideum and S. Purpusi both have bright green leaves and lack the peculiar habit of growth. S. monticola has shorter sepals, spreading pistils and white petals. Other species of the subgenus are even more dissimiliar.

Sedum torulosum first came to my attention in June, 1943, when Mrs. Ethel Rush of Los Angeles sent me a cutting of her number 18, said to have been collected originally near Saltillo, Coahuila, Mexico. Subsequently, Mr. Eric Walther of San Francisco sent under a manuscript name a living species which I have since grown in the greenhouse at Ithaca. More recently, Mr. Ferdinand Schmoll has sent a cutting of this same plant from his collection at Cadereyta in Queretaro, Mexico. None of the plants in cultivation at Ithaca have flowered, but M. and Mrs. Rush have had better luck in California. A few weeks ago Mrs. Rush kindly sent me one of two inflorescences which developed on her plant. From this specimen, the above description and the illustrations of the flowers are possible. The exact type locality is unknown, but possibly it is in the eastern part of the Mexican Highland, on the side that slopes towards the Gulf of Mexico. Rather than to risk error, it seems best not to be more definite about the exact locality. If the original plant really did come from the wild near Saltillo, that might in the future be designated as the type station.

For supplying material and information, I wish to express appreciation to Mr. and Mrs. Rush, Mr. Schmoll and Mr. Walther.

Department of Botany Cornell University Ithaca, New York

FIG. 102. A leaf rosette of Sedum torulosum nat. size.

FIG. 103. Flowering branch of Sedum torulosum.

FIG. 104. Sedum torulosum in the dormant stage, x 0.3.

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