Margaret A. T. Johnson

New chromosome numbers in petaloid monocotyledons and in other miscellaneous angiosperms

Summary. 502 chromosome counts are given for over 190 vouchered taxa in 32 genera representing 14 families, the majority of which are petaloid monocotyledons. Their significance is discussed.

An unusually high chromosome number in Voanioala gerardii (Palmae: Arecoideae: Cocoeae: Butiinae) from Madagascar.

Five seedlings germinated from the original collection (DransfieldJD6389), Kew accession number 588-86-05734, four of which were available for study. These are maintained in the Living Collections Department at Kew, and Fig. 1 shows one of the seedlings photographed in April 1988, 14 months after germination. One seedling is preserved in the Spirit Collection in the Herbarium at Kew where the holotype is also held, with seven isotypes lodged at other Herbaria (Dransfield 1989, in which locality information of this rare palm is also given). Young, rapidly growing root-tips were collected from the potted seedlings and two different pre-treatment agents tried. Root-tips were pre-treated either in 0-002M 8-hydroxyquinoline at i80C for 31 hours, or in a saturated aqueous solution of alpha-bromonaphthalene for 24 hours at 50-60C. Feulgen/orcein-stained squashes were prepared and made permanent as described previously (Johnson 1985). Photographs were taken on a Zeiss photo-microscope III, using phase contrast optics to improve definition.

Cytology of the highly polyploid disjunct species, Allium dregeanum (Alliaceae), and of some Eurasian relatives

Chromosome numbers are given for 16 taxa inAlliumSectionAllium, three in SectionCodonoprasum, two in each of SectionsMoliumandRhizirideumand one in each of SectionsKaloprasum,MegaloprasonandMelanocrommyum.The basic chromosome number is x=8 in all except SectionMolium, in which the studied species unusually have x=7. Polyploidy is common in the genus, with over half of the studied taxa in SectionAlliumhaving polyploid representatives. The highest ploidy levels found so far in the genus occur inA. dregeanum(2n=8x=64 and 10x=80), which is counted here for the first time. Although highly polyploid, this disjunct South African species forms only bivalents during meiosis. The chiasmata are proximal, an uncommon phenomenon reported also in hexaploidA. ampeloprasum. AlthoughA. dregeanumis genetically related toA. ampeloprasum, the suggestion that it is a cultivated variant of that species introduced to South Africa by the early settlers is unlikely.

Taxonomy of Cyanastroideae (Tecophilaeaceae): a multidisciplinary approach

Summary. Cyanastrum has previously been considered to include four species, all from the African continent. One of these, C. hostifolium from eastern Tanzania and northern Mozambique, is now transferred to a new genus, Kabuyea (K. hostifolia). This differs from Cyanastrum in several respects: vegetative morphology, perianth colour, anther dehiscence, pollen grain morphology, seed structure, chromosome number and karyotype. Karyotype analysis indicates that the individuals examined of the new genus are triploids. Analysis of rbcL DNA sequences for Cyanastraceae and Tecophilaeaceae places K. hostifolia as sister to C. cordifolium, but the level of sequence divergence between these two species is similar to that between genera in Tecophilaeaceae. The presence of a chalazosperm in seeds of Cyanastrum was the primary reason for former recognition of the monogeneric family Cyanastraceae, but this structure is absent from seeds of Kabuyea. Relationships of Cyanastrum and Kabuyea with other Tecophilaeaceae are discussed.

Cytology of Three New Geophytes from Turkey

The chromosome numbers of three new taxa, (one Alliaceae and two Hyacinthaceae) from Turkey are reported, together with the first chromosome record for the Turkish endemic, Muscari discolor, 2n = 18, (2x). The new taxa are Allium turcicum 2n = 16, (2x); Bellevalia anatolica 2n = 8, (2x); and Muscari anatolicum 2n = 18, (2x) and 2n = 36, (4x). One individual of A. turcicum was found to have an extra chromosome, 2n = 17 (16 + 1), a rare case of trisomy.

Two New Chromosome Numbers in an Unusual Albuca (Hyacinthaceae) from Saudi Arabia

The 50 taxa of the bulbous genus Albuca L. (Hyacinthaceae) grow throughout most of Africa, extending eastwards into the south western part of the Arabian peninsula. Albuca pendula B. Mathew in the subgenus Pallastema (Baker 1873) is an interesting new Saudi Arabian species which has recently been described by Mathew & Collenette (1994, 1997). This rare and unusual species is unlike any other Albuca, and indeed almost all other bulbous monocotyledons, in its long strap-like leaves up to 2 metres in length and 4 6 cm wide which hang down steep rocky cliff faces. Albuca pendula is related to A. abyssinica Dryand. which is common throughout East Africa and extends into the Arabian peninsula. The characteristic chromosomes of Albuca have been extensively studied by many workers. Most recently, Jong (1991) added 10 new counts, three of which were for new species which had been described by Hilliard & Burtt (1985). A study was undertaken of this new species to contribute further data to the cytology of the genus.