DESCRIPTION OF A SEDUM FROM ORIZABA, VERA CRUZ

By ROBERT T. CLAUSEN


The Sedum which is the subject of this dis­cussion has reached me from four different sources. In 1944, Mrs. Ethel Rush sent it under her No. 19. She had received it from Mr. Eric Walther as an undescribed species with white flowers. Mr. Walther in turn had obtained it in 1935 on a steep rocky hillside at Orizaba in the state of Vera Cruz, Mexico. Also in 1944, I received this same species from Mr. J. R. Brown whose material likewise had come from Mr. Walther. In 1949, Mr. E. J. Alexander of the New York Botanical Garden gave me a cut­ting of the same Sedum. He had obtained his specimen at a nursery in Mexico City. Finally, Mr. C. L. Cass sent me specimens of this species both in 1948 and 1949. The original source of his plants is unknown. All plants from the several sources are the same. They appear to be related to S. adolphii and S. nussbaumerianum but not a match for either species. In the following key, the distinguishing character­istics are indicated:


A. Cymes compound, dichasial; pedicels 2-4 mm. long; stamens 3-4 mm. long; leaves lustrous, dark green ............. Sedum from Orizaba

AA. Cymes compound, pleiochasial; pedicels 8.5-20 mm. long; stamens 5-7 mm. long; leaves lustrous or sublustrous ............ S.

B. Flowers at different levels in the cymes, not all in one plane; petals ovate-lanceolate, 3-3.5 mm. broad, white throughout; leaves strongly carinate dorsally, principal ones 8-10 mm. thick ......... S. adolphii

BB. Flowers appearing all in the same plane; petals linear-lanceolate, 1.5-3 mm. broad, pinkish dorsally; leaves convex, obscurely carinate dorsally, principal ones 5-8 mm. thick ............ S. nussbaumerianum


Walther published as fig. 26 on p. 71 of the Cactus and Succulent Journal, vol. 8, Nov., 1936, a photo of the new Sedum growing on rocks with a Begonia, near Orizaba. It was on a steep hillside to which he had been guided by Mr. Dorn. Echeveria nuda and Epidendrum radicans were on this same hillside. Walther did not describe and name the Sedum at the time when he published the photograph because he wanted first to study types in Europe. He did suggest, however, that it must be near to S. adolphii. Since 1944, I have tried in vain to match this particular Sedum with any previously named species. One idea, shared by Walther, was that it might be Hemsley's S. tortuosum. Study of a photograph of the type of S. tortuosum and careful perusal of the original de­scription have convinced me that Hemsley's species is not the same as the Sedum from Ori­zaba. According to Hemsley, S. tortuosum has spurred sepals whereas the sepals of the species from Orizaba are not spurred. Also, the type of S. tortuosum has leaves which are smaller, nar­rower and more definitely spatulate. My opin­ion now is that S. tortuosum may be a synonym of S. amecamecanum Praeger, but enough doubt exists that Praeger's clearly typified name should not be displaced by the earlier one of Hemsley. Other old names proposed in Sedum do not seem to apply to the white-flowered species from Orizaba. For that reason, I am proceeding to describe this as a new species, indicating in the specific epithet one of its distinctive features, namely the lustrous leaves.



Sedum lucidum, sp. nov.,


subgeneris Pachysedum, sectionis Pachysedum (Eupachysedum). Suffrutices glabri, caulibus decumbentibus, 5-7 mm. in diam., ad 35 cm., surculis sterilibus erectis ad basim; folia spiraliter alterna, divaricata, oblongo-elliptica vel spatulato-oblonga, sessilia, breve calcarata, acuta ad apices, aliquanto angulata et carinata, plus vel minus plana ventraliter et convexa inaequaliter carinata dorsaliter, minimum sursum curva, viridia et lustra, 0.7-4.8 cm. longa, 6-19 mm. lata, 3.6-10 mm. crassa; caules floriferi axillares, divaricati, in axillis foliorum superorum, 6-15 cm. longi, foliis remotis, ovato-ellipticis, breve calcaratis, acutis vel obtusis, chloris et lucidis, 3.4-12 mm. longis, 2-5 mm. latis; cyrnae compositae, dichasia, 3.5-6 cm. in diam.; flores plerumque 5-partiti. rariter 4-partiti, 9-11 mm. in diam., moschato-odorati, in pediculis puniceis, 2-4 mm. longis; sepala inaequalia, oblonga vel lanceolata, obtusa, erecta, lucida, viridia, 2-4 mm. longa, connata ad basim 1 mm.; petala elliptico-lanceolata, acuta, mucronato-appendiculata, late divaricata super bases suberectas, 5-6 mm. longa, 2-2.2 mm. lata, connata infra 0.6 mm., alba; stamina 2.4-4.4 mm. longa filamentis albis et antheris luteis, epipetala adnata 1.2-1.5 mm. super bases; squamae transverse oblongae, erosae, emarginatae, 0.3-0.7 mm. longae, 0,6-0.7 mm. latae, galbanae vel albae, pistilla erecta, stylis subdivaricatis, 4-4.6 mm. longa, pallide chlora. Floret ab Novembre ad Martium. Typus est planta culta in Ithaca, N. Y., 1951, Jan. 3, C 44-12, originaliter ab Orizaba, Mexi­co, ubi Eric Walther eandem collegit.


Sedum lucidum belongs to the subgenus Pachysedum and section Pachysedum (Eupachysedum). The plants are glabrous subshrubs with decumbent stems, reddish brown below, green upwards, 5-7 mm. in diameter, to 35 cm. long, towards base giving rise to erect sterile shoots; leaves alternate, widely spreading, oblong-elliptical or spatulate-oblong, sessile, short-spurred, acute at apex, somewhat angulate and keeled, more or less plane ventrally and convex and unevenly keeled dorsally, slightly upcurved, 0.7-4.8 cm. long, 6-19 mm. wide, 3.6-10 mm. thick, dark green and lustrous, especially when young; floral stems axillary, 6-15 cm. long, divergent, in the axils of the upper leaves; floral stems with the leaves remote, ovate-elliptic short-spurred, acute or obtuse, light green and very lustrous, 3.4-12 mm. long, 2-5 mm. wide; cymes compound, dichasia, 3.5-6 cm. long, 4-6 cm. wide; flowers mostly 5-merous, rarely 4-merous, 9-11 mm. in diam., with musky fra­grance, on flesh-colored pedicels, 2-4 mm. long; sepals very unequal, oblong to lanceolate, blunt, erect, lustrous, green, 2-4 mm. long, connate at base for 1 mm.; petals elliptic-lanceolate, acute, mucronate-appendaged, widely spreading above the suberect bases, 5-6 mm. long, 2-2.2 mm. wide, connate at base for 0.6 mm., white; sta­mens 2.4-4.4 mm. long with white filaments and yellow anthers, the epipetalous on the petals 1.2-1.5 mm. above their bases; nectaries trans­versely oblong, erose, emarginate, 0.3-0.7 mm. long, 0.6-0.7 mm. wide, pale greenish yellow or white; pistils erect with styles subdivergent, 4-4.6 mm. long, greenish white or very pale yel­low. Flowers from November to March. The type is a specimen cultivated in the greenhouse at Ithaca, N. Y., C 44-12, Jan. 3, 1951. It came originally from near Orizaba, Mexico, where Eric Walther collected it in 1935.


S. lucidum is the eighth species of Sedum which I have recorded from Vera Cruz. The others are S. dendroideum, S. purpusii, S. botteri, S. nussbaumerianum, S. obcordatum, S. hemsleyanum, and S. moranense. S. aoikon possibly is native near Orizaba, but its occur­rence there should be verified before it is in­cluded definitely in the list for Vera Cruz. S. dendroideum, S. purpusii, S. botteri and S. obcordatum all have yellow petals. S. hemsleyanum is an herb. S. moranense has closely crowded, small ovate leaves and kyphocarpic pistils. S. nussbaumerianum, with flowers on long pedi­cels, is most closely related to S. lucidum. Like­wise, S. adolphii is related. That still has not been found at any definite locality in Mexico. When something is known concerning the varia­tion of S. adolpbii in the wild, the status of S. nussbaumerianum will need to be reappraised: Uhl*, who has studied some of my plants cytologically, has reported gametic numbers of 64 for one plant of S. adolpbii and three plants of S. nussbaumerianum. For S. lucidum, listed as "near tortuosum Hemsley," "Clausen's species No. 503," he reported a gametic number of 34 chromosomes for a plant of the type collection. These data suggest that the origin of S. adolphii and S. nussbaumerianum from their nearest rela­tives must have involved both an adjustment in the basic number of chromosomes and the at­tainment of a higher level of polyploidy. On a basis of morphological evidence, S. lucidum im­presses me as the most primitive and S. nussbaumerianum as the most advanced of this group of three species.


The only noteworthy variation of S. lucidum that has come to my attention is a cristate condi­tion which has developed spontaneously in two of my plants.


In conclusion, I wish to thank all those who by supplying specimens or information have made possible the preparation of the above account. Particularly, I wish to express appre­ciation to Mrs. Ethel Rush, Mr. E. J. Alexander, Prof. A. L. Andrews, Mr. J. R. Brown, Mr. C. L. Cass, Dr. C. H. Uhl and Mr. Eric Walther.


Department of Botany

Cornell University

Ithaca, New York


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*) Uhl, C. H. A cytotaxonomic study of the Crassulaceae. Manuscript thesis, Cornell University, p. 1-203, pl. I-VIII. 1947.


© Cactus & Succulent Journal of America, 1951