Chromosome numbers in Compositae. XVIII.

Chromosome numbers and other cytogenetic data were determined from microsporocytes in 316 collections including 13 tribes of Compositae, mostly from Africa, Australia, Mexico, Central America, and South America. First reports are provided for 66 species and the genera Cassinia (2n ≈ 14_II), Feldstonia (2n = 11_II), Gochnatia (2n ≈ 23_II), and Pseudoconyza (n = 10). In addition, new chromosome numbers are established at the generic level in Acourtia, Calea, Craspedia, Gnaphalium, Helipterum, Liabum, Leucheria, Smallanthus, Trixis, and Viguiera and at the specific level in 13 additional species.     

Chromosome numbers of Mongolian Angiosperms. II.

Chromosome numbers are reported for 20 collections of Mongolian plants representing 19 taxa. The first chromosome records are reported forArabidopsis mongolica (2n=16),Caragana pygmaea (2n=16),Isatis costata var.leiocarpa (2n=28),Lophanthus chinensis (2n=18) andStevenia cheiranthoides (2n=32). Counts partly differing from those previously recorded are given forBatrachium trichophyllum subsp.trichophyllum (2n=32+0-2B, 36+6B),Cuscuta chinensis (2n=60),Dracocephalum fragile (2n=72) andErysimum flavum (2n=14). Chromosome numbers of the following taxa were confirmed:Astragalus monophyllus (2n=16),Erodium stephanianum (2n=16),Gastrolychnis apetala (2n=24),Geum aleppicum (2n=42),Linum baicalense (2n=18),Rorippa palustris (2n=32),Rubia cordifolia subsp.pratensis (2n=22),Schizonepeta multifida (2n=12),Tribulus terrestris (2n=36) andVicia cracca (2n=14). Taxonomic remarks onArabidopsis mongolia, Erysimum flavum, Stevenia cheiranthoides andVicia cracca are added. A new combinationArabidopsis mongolica (Botsch.)Měsí?ek & Soják is proposed.     

Chromosome numbers of Thai Rubiaceae

Chromosome numbers for 14 taxa of indigenous Thai Rubiaceae are presented. They include first counts for 3 genera: Aphaenandra (A. uniflora), Prismatomeris (P. tetrandra subsp. malayana) and Tarennoidea (T. wallichii) ; all show diploidy on x=11. The remaining counts are first counts for species: Argostemma diversifolium, A. neurocalyx and A. pictum, Coptosapelta flavenscens, Gardenia saxtilis, Ixora sp., Morinda sp., Mussaenda sanderiana, Oxyceros horridus, Rothmannia wittii (first count for an Asiatic species of the genus) (all diploid on x=11), and Canthium sp. (tetraploid on x=11). The poor state of karyological knowledge of indigenous Thai Rubiaceae is discussed, and a table including all relevant known chromosome counts is presented. Chromosome data are only known for 38 genera (ca. 41% of all Rubiaceae genera occurring in Thailand); chromosome numbers are often only available for one or few taxa of each genus [in sum, for only about 50 (or for roughly 10% of all) taxa]. Of only 14 genera (ca. 15%), chromosomes were counted from Thai material (for the others, counts originate from elsewhere, i.e. refer to more widely distributed taxa also extending into Thailand).     

Chromosome numbers in the genus Mentha L.

One hundred and fifty-seven chromosome numbers of a range of taxa from both hemispheres are reported in the genus Mentha. Plants of both wild and cultivated origin have been sampled, including hybrids, some of which have been synthesized from known parents. Some of the causes of the great taxonomic complexity of the group are discussed and the need for accurate and unambiguous identification of the plant material is stressed. There is a critical review of the chromosome numbers in relation to their taxonomy, with a discussion on probable basic numbers. The most useful areas of future research are indicated.     

Chromosome numbers and reproduction inRubus subgen.Malachobatus

A review of current knowledge of chromosome numbers and modes of reproduction in the genusRubus L. is presented. Chromosome numbers from some species of subg.Malachobatus Focke together with results of crossing experiments are reported for the first time.     

Chromosome numbers of dominican compositae

Chromosome numbers of 34 species of Dominican Compositae in 26 genera and nine tribes are reported. First counts are given forCoreopsis buchii (2n = 64),Lagascea mollis (2n = 34),Spilanthes urens (n = 16),Liabum subacaule (n = 18),Eupatorium sciatraphes (2n = 40),Hieracium gronovii (2n = 18),Vernonia buxifolia (2n = 34),V. sprengeliana (2n = 34),V. racemosa (2n = 28), andChaptalia leiocarpa (2n = 48,ca. 58). Our report forNarvalina domingensis (2n = 120) is the first for any species of this genus.     

Chromosome numbers in Nigerian Compositae

Chromosome counts are presented for 54 collections of Nigerian Compositae. The collections comprise 37 taxa belonging to 21 genera and 34 specieS. Most of the taxa studied are colonisers of disturbed habitats.     

Chromosome numbers in Malawian Commelinaceae

In this account chromosome numbers of 22 species and varieties from five genera of Commelinaceae occurring in Malawi are given. For 14 of them this is the first time their chromosome numbers have been reported. A wide range of chromosome numbers of 2n = 26 , 28, 30. 44. 52 and 60 is noted in Commelina.     

Chromosome numbers in Brachypodium Beauv. (Gramineae)

A summary of previous chromosome counts of Brachypodium is given in addition to a large number of new reports. The present work does not support claims made for extensive infraspecific variation in certain species. The implication of cytological knowledge for a taxonomic and evolutionary understanding of the genus is discussed.