Contributions to a chromosome atlas of the New Zealand flora ‐ 38. Counts for 50 families

Abstract

Documented chromosome numbers are reported for 187 taxa (170 species, 9 subspecies, 8 varieties), 5 hybrids (four putative, one artificial), and 18 of uncertain rank from 50 families (84 genera; 2 lycophyte, 11 pterophyte and 71 anthophyte). Of these, 189 counts are new for the New Zealand flora (167 of these are from named taxa). Many of the counts reported are from more poorly investigated families (e.g., Cyperaceae, Lycopodiaceae, Potamogetonaceae) and genera (e.g., Desmoschoenus, Freycinetia, Lycopodiella, Lycopodium, Potamogeton, Schoenus) indigenous to New Zealand, or from nationally uncommon and/or threatened taxa (e.g., Eleocharis neozelandica, Hebe societatis, Myriophyllum robustum, and Pittosporum dallii) and/or newly described plants (e.g., Gingidia grisea, Olearia adenocarpa), while three counts are from naturalised species (Alternanthera sessilis, Nephrolepis cordifolia, and Senecio skirrhodon), and one from a cultivated plant of Metrosideros nervulosa. In the majority of genera the numbers follow established patterns. Counts have now been B04002;

Chromosome numbers of selected species of Elatine L. (Elatinaceae)

“…We also confirmed the same chromosome number (2n = 36) for E. alsinastrum, in line of what was previously reported [22]. Actually, it was suggested that 2n = 36 is the most common number and the lowest number of chromosomes in species of Elatine genus, as it was also found in the recently described species E. gratioloides [21], and the species with the widest distribution range in the genus, E. triandra [17]. In this study we showed that E. triandra can also have 2n = 54 chromosomes, thus the tetraploid and hexaploid level can coexist in the genus.…”

“…[19], E. hexandra (Lapíerre) DC [20], E. gratioloides A. Cunn. [21], E. alsinastrum L. [22] and E. gussonei (Sommier) Brullo, Lanfr., Pavone & Ronsisv. [23].…”

Short Communication. A robust method for chromosome quantification and ploidy determination in woody species

“…For example, in laboratorygenerated polyploids, reciprocal loss or silencing of duplicated genes can lead to hybrids that lack both copies of a duplicated gene pair (Soltis et al 2004) and, thus, accurate ploidy determination via chromosome counting is required in addition to flow cytometry. Root tips are commonly used for chromosome counting (Hanson 2001;De Lange et al 2004;Vallès et al 2005). Our method can be used with root or shoot tips and was successfully used in species with small and numerous chromosomes.…”

“…Chromosome counting in actively growing root-tip cells is the unambiguous method for ploidy assessment (De Lange et al 2004;Bachir and Abdellah 2006;Ochatt 2008) and mostly involves root-tip squashes and commonly used light-microscopy stains such as aceto-carmine. However, this technique can fail in species with many small chromosomes, such as Acacia mearnsii (Beck et al 2003a), and obtaining actively growing root tips from field-grown trees is difficult.…”

Plagianthus regiussubsp.chathamicus(Malvaceae)— a new combination for a Chatham Islands endemic tree

“…One particular Chatham Islands issue to resolve has been determining the status of Cockayne's Plagianthus. Having now critically studied P. regius throughout New Zealand, it is clear to me that the Chatham Island plant is very similar, there being no clear-cut distinctions in juvenile/adult leaf shape, size, or floral and fruit morphology, or cytology (de Lange et al 2004). The only obvious difference, as Cockayne himself made clear (1902,1912), is the lack of a divaricating, juvenile stage in the Chatham Islands plants.…”