Lenophyllum

Abstract: Chromosome numbers are reported for probably all 11 species of Graptopetalum (x = 30-35) and for both species of Thompsonella (x = 26). Plants of two species of Graptopetalum have gametic numbers from about 240-275, more than have been reported in any other seed plants. In hybrids the 30-35 chromosomes in the basic genome of Graptopetalum and likewise the 26 in Thompsonella apparently do not pair among themselves, and the genomes seem to be no more potent genetically than those of other species in their subfamily having as few as 12 chromosomes. Species with these gametic numbers are therefore considered to be diploid. On the other hand, in hybrids between a diploid and a plant with a very high chromosome number the phenotype of the latter predominates, and most of its chromosomes pair with each other. Many such hybrids are fertile. These facts suggest that the high polyploids arose by autoploidy rather than by alloploidy. Nevertheless, they may store heterozygosity at some gene loci and release it in various dosages and proportions each generation. PROBABLY more than 250 species of Crassulaceae are native to Mexico. Most authors today (e.g., Jacobsen, 1960) classify them in nine genera: the small annual, world-wide Tillaea (?Crassula); Dudleya (occurring in M\Jexico only north and west of the Gulf of California); Echeveria; Graptopetalum; Lenophyllum; Pachyphytum; Sedum; Thompsonella; and Villadia (including Altamiranoa). This paper reports the chromosomes of probably all known species of Graptopetalum and Thompsonella and of two artificial hybrids, with a discussion of the very high chromosome numbers found in two species. Graptopetalum was established by Rose (1911) for G. pusillum. Three species described earlier have been transferred from other genera, and seven probably valid species have been described later, for a otal of probably 11 known species, ranging from central Arizona to Oaxaca. The inflorescence is a lateral cyme or panicle. The flowers are usually fetid, and the petals are pale, erect, and connate in the lower half, rotate in the distal half, where they are marked (sometimes weakly, sometimes strongly) with tiny reddish to brownish dots (pigmented epidermal cells) that are usually clustered to form bands of color across the petals. The stamens are erect at first, then after anthesis become strongly recurved against or between the petals and away from the carpels before the stigmas are receptive. The species differ greatly in vegetative characters. 1 Received for publication 11 May 1970. I am indebted to Dr. Reid Moran, Natural History MIuseum, San Diego, California (collection numbers preceded by M), and to Mr. Paul Hutchison, formerly of the University of California Botanical Garden, Berkeley (collection numbers preceded by UC), for many plants and identifications and for many fruitful exchanges of ideas. Six form essentially acaulescent rosettes, some with offsets; one (G. pachyphyllum) is somewhat creeping and tufted; two (G. amethystinum and G. paraguayense) are pendent and have very thick leaves; and two (G. fruticosum and G. grande) are bushy, in the latter case up to a meter or more high. Various species of Graptopetalum have been assigned at one time or another to six other genera: Cotyledon, Dudleya, Echeveria, Pachyphytum, Sedum, and the monotypic Byrnesia. In the last general treatment of the Crassulaceae, Berger (1930) assigned three of its species to a special section under Sedum; another (G. filiferum) to a different section of Sedum; G. rusbyi to his section Dudleya of Echeveria; and G. amethystinum to Pachyphytum. Thompsonella was proposed as a genus by Britton and Rose (1909) for two species of south central Mexico. Both species are acaulescent, and their flowers are crowded on slender, erect, lateral thyrses (sometimes spikes in the upper part or on improverished specimens), unlike anything in Graptopetalum. Again the petals are erect and connate in the lower half, then bend sharply out to become rotate. However, the corolla is smaller than in Graptopetalum and mostly reddish brown with a yellowish margin. The stamens remain erect and do not recurve. The species have been assigned by various authors to Echeveria (Berger, 1930), Graptopetalum, and Villadia. 1\Iost authors who have studied it recently accept Thompsonella as a genus (Moran, 1969). Chromosomes were studied from conventional aceto-carmine preparations of meiosis in microsporocytes. For most collections with high chromosome numbers the best available metaphase I figures were sketched with the aid of a

Abstract: Background: Echeveria and Pachyphytum are two closely related Neotropical genera in the Crassulaceae. Several species in Echeveria possess characters cited as diagnostic for Pachyphytum such as a clearly defined stem, a nectary scale on the inner face of petals and as inflorescence a scorpioid cyme or cincinnus. Pachyphytum has been identified as monophyletic while Echeveria as polyphyletic in previous molecular phylogenetic analysess. Hypothesis: The objective of this paper is to identify the phylogenetic position of a rare species with restricted distribution in Echeveria , E. heterosepala that possesses the diagnostic characters of Pachyphytum to better understand the generic limits between these two genera. We expect this species to be closely related to Pachyphytum . Methods : Bayesian inference and Maximum Likelihood analyses were carried out using 47 taxa, including as ingroup, species of Echeveria, Graptopetalum, Lenophyllum, Pachyphytum, Sedum , Thompsonella and Villadia and as outgroup, species in Dudleya . Analyses were conducted based on plastid ( rpl16, trnL-F ) and nuclear (ETS, ITS) markers. Ancestral character reconstruction was carried out under a parsimony criterion based on the molecular trees retrieved by the phylogenetic analyses. Four morphological characters were considered: defined stem, type of inflorescence, nectary scale in petals and position of sepals. Results : Accessions of E . heterosepala were retrieved in a well-supported clade group comprising exclusively Echeveria species. Therefore this species belongs to Echeveria although possessing characters similar to Pachyphytum and moreover it was not identified closely related to this genus. None of the traits considered have taxonomic importance. The node at the Pachyphytum clade identified unambiguous character states such as stem present, straight sepals, nectary scale on petals, however these character states were identified in the rest of the clades as well. Remarkably, the monophyly of Pachyphytum was corroborated, while Echeveria remains poorly understood.