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Three new species of Ocotea (O. disjuncta, O. iridescens, and O. rovirosae) from southern Mexico are described and illustrated. Ocotea disjuncta is related to the O. effusa group, while O. iridescens seems to be related to the O. heydeana group. The relationships of O. rovirosae are not clear.
Poaceae in the Robinson Crusoe (=Juan Fernández) Islands number 53 species in 32 genera, of which 9% of the species are endemic, 9% indigenous, and 81% adventitious. The endemic taxa (and their conservation status) are: Agrostis masafuerana (rare), Chusquea fernandeziana (not endangered), Megalachne berteroana (not endangered), M. masafuerana (not endangered), and Podophorus bromoides (extinct). Megalachne and Podophorus are endemic genera. Comparisons with Poaceae in the Bonin and Volcano Islands, Canary Islands, Galápagos Islands, and Hawaiian Islands show different levels of endemism: number of endemic taxa, respectively, 5, 10, 12, 40; percent specific endemism, 8, 6, 21, 19. No endemic genera occur. Anthoxanthum odoratum, Avena barbata and Hordeum murinum are noxious weeds in the Robinson Crusoe Islands. Many adventives are shared among floras of the archipelagos, with the highest ties of Robinson Crusoe being to the Canaries (53% of total Poaceae known in Juan Fernández) and the Hawaiian Islands (47%). Low levels of adventives occur within the Bonin (5%) and Galápagos (7%) Islands. In contrast, there are many endemic genera of Asteraceae in these same archipelagos: Bonin and Volcano Islands (1), Canary Islands (8), Galápagos Islands (5), and Hawaiian Islands (6); percent of specific endemism is also higher (20, 53, 54 and 56, respectively). Hypotheses for greater levels of endemics among oceanic island Asteraceae include more efficient dispersal mechanisms by wind and birds, animal pollination systems that result in greater degrees of geographic populational genetic isolation, and a vascular cambium that offers enhanced growth-form evolutionary opportunities.
Tagetes moorei var. breviligulata is proposed as new. It differs from the typical population in habit, number of flowers, and size of the ray flowers. It is known from eastern Querétaro state, México. Descriptions, an illustration, a key, and a tabular comparison are provided.
Reported in this paper is a karyomorphological study on one natural population of each of eight varieties in the Spiraea japonica complex. The interphase and mitotic prophase can be classified into the simple chromocenter type and the proximal type, respectively. The metaphase karyotypes of the eight varieties were formulated as follows: S. japonica var. japonica: 2n = 18 = 14m 2sm 2st; S. japonica var. acuta: 2n = 18 = 11m 4sm 3st; S. japonica var. incisa: 2n = 18 = 12m 4sm 2st; S. japonica var. stellaris: 2n = 18 = 15m 1sm 2st; S. japonica var. acuminata: 2n = 18 = 14m 2sm 2st; S. japonica var. ovalifolia: 2n = 18 = 10m 2sm 2st 4t; S. japonica var. glabra: 2n = 18 = 10m 4sm 4st; S. japonica var. fortunei: 2n = 36 = 17m 16sm 3st. Karyomorphological study reveals that the chromosome numbers within the complex are stable, and that karyomorphological divergence between the varieties lies mainly in chromosome size and organization. Based on the karyomorphological data and geographical distribution of the complex, the differentiation pattern as well as evolutionary mechanism of the complex is evaluated.
Leskeodon caducifolius is described from recent collections made at a single site in a cloud forest in southern Ecuador. The species is distinctive in its small, caducous leaves and elongate, porose exothecial cells.
Verbesina barrancae, a new species of Compositae (Heliantheae) from Jalisco, México, is described and illustrated. It is morphologically similar to Verbesina crocata but differs in characteristics of inflorescence, anthers, and achenes as well as in form of pollen, size and number of spinules, size of colpus transversalis, and index of polar area.
Castilleja hidalgensis is described from several collections from xeric limestone sites in central Hidalgo, Mexico. The new species belongs to a small complex of poorly known and uncommon species within sect. Euchroma, sharing important characteristics with C. macrostigma, the first-described taxon in this assemblage. The new species appears to be rare and highly restricted both geographically and ecologically. A key to the species of the C. macrostigma group is provided.
The pericarp structure of representative species of the four genera of the subtribe Linospadicinae is described and compared. Tissues found in the pericarp of this group are similar to those found in other subtribes of the Areceae, with no characters unique to the subtribe and nothing to suggest its closest affinities. The four genera, as well as each species examined, do show distinctive pericarp features, however. Laccospadix and Linospadix are similar, both with a single series of fibrous bundles and an outer series of prominent raphide-bearing cells dominating the pericarp. In both Howea and Calyptrocalyx, a complex exocarp forms from a series of fibrous bundles and brachysclereids, but each genus has other distinctive characters. Howea has vascular bundles in the exocarp zone, an outer series of raphide-bearing cells, and a conspicuously thickened locular epidermis. Based on a limited sample of four species, raphide-bearing cells appear to be always interior to the exocarp in Calyptrocalyx, and the locular epidermis is thin.
Specimens representing Geonoma stricta, a widespread species in the Amazon region, are variable morphologically, especially in leaf size and shape. Ordination and clustering of quantitative morphological variables indicate that the specimens can be classified in at least four different ways, but none of these is fully supported by Discriminant Analysis. The problem revolves around a group of specimens with intermediate leaf size and shape. Mapping of specimens shows that no grouping is geographically separate from any other. An infraspecific classification is not possible based on the data analyzed here. Principal Component Analysis and a test of hybridity indicate that a small percentage of specimens might be of hybrid origin.