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doi: 10.1111/j.1095-8339.1996.tb00476.xpmid: N/A
AbstractQuantitative and qualitative data are presented for 11 collections of six species. The wide range of character states for the species is presented in the form of a key to emphasize their potential systematic correlations. Distinctive among these are phellem characteristics. Fibre-tracheids are newly reported for lianoid Gnetum species. Cells previously thought to be like companion cells in secondary phloem are shown to be uniseriate rays, counterparts to uniseriate xylem rays. Laticifers are abundant in most of the species, and are newly described for secondary tissues of Gnetum. Presence of tyloses in laticifers of two species is apparently a new report for vascular plants. Tori are present in two New World Gnetum species, adding to the report in African species. Perforation plates are simple except near or in primary xylem, where they are simple or foraminate. Torus presence and foraminate perforation plate presence are features more reminiscent of Ephedra and other gymnosperms than of angiosperms. The bark of Gnetum is also very similar to that of Ephedra.
doi: 10.1111/j.1095-8339.1996.tb00477.xpmid: N/A
AbstractThe circumscription of the two Arabian species Sarcostemma forskaolianum Schult. and S. vanlessenii Lavranos is clarified. S. vanlessenii is identified as a widespread species, occurring in East Africa and the southern Arabian Peninsula. Within the Sarcostemma viminale complex, three new subspecies are delimitated. Subspecies odonlolepis (Balf.f.) Meve & Liede, comb, et stat. nov. is established for glabrous, strongly twinning plants close to those of subspecies brunonianum (Wight & Am.) P.I. Forst., but distinguished by flower-bearing laterals and an outer corona half as high as the gynostegium. Ecologically, this taxon is confined to coastal habitats in East Africa. Subspecies stipilaceum (Forssk.) Meve & Liede, comb, ct stat. nov. covers stout, non-twining representatives of East Africa and Arabia, also with short flower-bearing laterals. Subspecies suberosum Meve & Liede, subsp. nov. is newly described to accommodate the most frequent East African form of S. viminale, often mistaken for the typical subspecies. All taxa are described in detail, chromosome numbers are given and distribution maps are provided for S. forskaolianum, S. vanlessenii and S. viminale subsp. odontolepis. A synopsis of all taxa occurring in East Africa and Arabia and additional chromosome numbers are provided.
doi: 10.1111/j.1095-8339.1996.tb00478.xpmid: N/A
AbstractThe British elms have historically proven to be recalcitrant taxonomically, with at least six different levels of treatment being applied. The taxonomic history of the group and the nomenclature is outlined from the ancient authors up until the present day. This paper is the foundation for future articles in which a novel taxonomic treatment is introduced.
KOKUBUGATA, GORO; KONDO, KATSUHIKO
doi: 10.1111/j.1095-8339.1996.tb00479.xpmid: N/A
AbstractSimilar karyotypes of In = 22 in Cycas circinalis, C. media var. basaltica, C. revoluia var. rewluta, C. revoluta var. taiwaniana and C. siammsis were compared with each other by using the CMA and DAPI fluorescent staining methods. Their four largest submedian-centromeric chromosomes each had a CMA band at the terminal region in common. Their 12 terminal-centromeric chromosomes commonly displayed CMA bands at the terminal region and the pericentric region. Two of the 12 terminal-centromeric chromosomes carried a CMA band somewhere in the interstitial region of the long arm. C. circinalis alone showed it at a relative position closer to the centromere. The other taxa showed it at a relative position near the terminal region. All of the chromosomes exhibited the DAPI dot at the centromeric region.
GIELLY, LUDOVIC; TABERLET, PIERRE
doi: 10.1111/j.1095-8339.1996.tb00480.xpmid: N/A
AbstractPhylogenetic relationships between the European species of the genus Gentiana L. (Gentianaceae) were inferred from chloroplast trnL, (UAA) intron sequence data. The phylogeny obtained is largely in accordance with the classification of species into sections Gentiana, Megalanthe and Calathianae. Few synapomorphies support the branching of the main lineages and thus could suggest a rapid radiation following the colonization of Europe. Within section Gentiana, our results are highly congruent with the previous distinction of G. montserratii Vivant from G. lutea L. Section Megalanthe is divided into two well separated lineages, both of which comprise calcicole and calcifuge species. The ‘star phylogeny’ obtained in section Calathianae suggests that most of the taxa speciated almost simultaneously. Relative-rate tests between two lineages suggested that section Chondropliyllae displays higher mutation rates than the rest of the genus Gentiana and that cpDNA can violate assumptions of rate constancy at lower taxonomic level.
VOVIDES, ANDREW P.; OLIVARES, MARIANA
doi: 10.1111/j.1095-8339.1996.tb00481.xpmid: N/A
AbstractThe cycad %amia loddigesii Miq. forms a morphologically variable complex on the Yucatan peninsula, Mexico. Several diploid chromosome numbers have been found in the species: In = 17, 24, 25, 26 and 27. Differing karyotypes and chromosome numbers were found in individuals of the same population and die karyotypes differ widely in numbers of metacentric and telocentric chromosomes present. Centrometric fission as well as pericentric inversions and unequal translocations are suggested to be the probable mechanisms for this karyotype variation. There appears to be a correlation between high chromosome number and increasing dryness of the habitats. Coupled with the strongly asymmetrical karyotypes, this suggests that karyotype evolution in Z- loddigesii is recent.
Dickie, John; Cribb, Phillip; Spellerberg, Ian; Brightman, Frank; Fischer, Eberhard
doi: 10.1111/j.1095-8339.1996.tb00482.xpmid: N/A
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