No abstract

A method was designed and validated for the analysis of dihydroxyacetone in the floral nectar of ma̅nuka (Leptospermum scoparium). The method was applied to samples collected from different regions of the North Island and the Nelson region of the upper South Island of New Zealand during the period 2009-2012 as well as to nectar samples from some Australian Leptospermum species. The ratio of dihydroxyacetone to total sugar (DHA/Tsugar) was classified as low (<0.001 mg/mg), moderate (0.001-0.002 mg/mg), or high (>0.002 mg/mg). Inter- and intraregional variation were observed as well as interannual variation with variation from low to high classification occurring within one region and from low to moderate between years. Australian species also demonstrated elevated levels of dihydroxyacetone in the nectar. Some garden cultivars were shown to produce very high nectar DHA/Tsugar, and a survey of cultivars was undertaken; cultivars with single-flowered red or pink flowers were the most common producers of very high nectar DHA/Tsugar.

The quadriflagellate snow alga Chlainomonas Christen, distributed in New Zealand and North America, has several unusual structural attributes. A process assumed to be cytokinesis involves extrusion of protoplasm from the parent through a narrow canal, C. kolii (J. T. Hardy et Curl) Hoham produces a net-like outer envelope rather than a cell wall, and the flagellar basal apparatus of Chlainomonas consists of two semi-independent pairs of basal bodies. Structural connections between basal body pairs appear minimal, but a connecting system different from that observed in other genera exists within each pair. Phylogenetic analysis using rbcL sequences places Chlainomonas in the Chloromonas clade, other known members of which are all biflagellate. Chlainomonas is split into two robust lineages, with New Zealand collections sharing an origin with northern North American collections. Although the quadriflagellate condition is regarded as ancestral in the Chlorophyceae, we speculate-based on ultrastructural and molecular data presented here-that Chlainomonas represents a derived form that has arisen from fusion of two ancestral biflagellate cells. Other explanations (for example, that Chlainomonas represents a diploid form of a biflagellate species) are remotely possible but are presently at odds with extensive observations of field material. Improvements in techniques for experimental manipulation of these sensitive cryophiles will be required to fully characterize their structure and progress our understanding of their biology.

Chromosome numbers are documented for 122 taxa in 44 genera from 22 angiosperm families in the New Zealand region. Counts for comparison are also reported for 3 species indigenous to Australia.

Field surveys were undertaken of Abstract Field surveys were undertaken of Abstract Brassica naturalised in Canterbury, investigating taxonom-ca naturalised in Canterbury, investigating taxonom-ca ic diversity, morphological variation, distribution, and abundance of naturalised taxa, crop escapes, and crop-weed hybrids. As a result, six species, nine varieties, and two natural hybrids were recognised as naturalised in Canterbury. B. rapa var. oleifera was the most common taxon, while B. rapa var. chinensis, B. rapa var. glabra, B. rapa var. rapa, B. napus var. oleifera, and B. oleracea var. acephala were less abundant and generally occured in small populations of only a few individuals in rural areas. Single plants of B. oleracea var. gongylodes (kohl rabi) and B. napus var. napobrassica (swede) were collected. An additional species, B. juncea, is recorded as a new naturalised plant in Canterbury. Most of the Brassica populations sampled were small, with 64% of the 107 populations observed comprising fewer than 10 plants.Flow cytometry profi les were obtained for 168 samples of B. juncea, B. napus, B. oleracea, and B. rapa, and these usually confi rmed morphological identifi cations to a particular species. However, there were some identifi cation uncertainties with B. napus, as some plants had a fl ow cytometry profi le of that species but the morphology of either B. rapa var. oleifera or B. oleracea var. acephala. Tetraploid plants of B. rapa (var. chinensis, var. oleifera, and var. rapa) and B. oleracea var. acephala were recorded. We also identifi ed two instances of hybridisation. One plant has a fl ow cytometry profi le and a high percentage of malformed pollen that are consistent with being the putative interspecifi c F 1 hybrid B. napus × B. rapa. Another population included plants of the putative intraspecifi c hybrid B. rapa var. oleifera × B. rapa var. chinensis growing with the two parental species.