Alseuosmia

Abstract: The secondary xylem of five species representing all three genera of Alseuosmiaceae was studied. Salient anatomical features that circumscribe the family include narrow vessel ele- ments with many-barred, scalariform perforation plates, pores distributed as a combination of both solitary elements and radial multiples, living septate fibers with stored starch at maturity, and the scarcity or absence of axial parenchyma. An absence of rays characterizes Alseuosmia and Wittsteinia vacciniacea. The insular species, W. balansae from New Caledonia, contains exclusively multiseriate rays that are very wide and tall and composed completely of erect and square cells. The large rays and the occasional scalariform lateral wall pitting of vessel elements of this species are probably best interpreted as paedomorphosis related to the increased size of this plant. The ancestral habit of the family remains unclear since Crispiloba disperma has retained a more primitive xylem structure as evidenced by the occurrence of axial parenchyma and shorter and narrower heterocellular rays. Xylem anatomy can be used to support a position for the Alseuosmiaceae in or near the woody Saxifragaceae.

Abstract: A new species Alseuosmia turneri R. O. Gardner (Alseuosmiaceae Airy Shaw) from the Volcanic Plateau. North Island, New Zealand is described and illustrated. A. linariifolia A. Cunn. is reduced to a variety of A. banksii A. Cunn. and A. quercifolia A. Cunn. is given hybrid status ( = A. banksii A. Cunn. × A. macrophylla A. Cunn.). A key to the four Alseuosmia species, synonymy, and a generalised distribution map are given. A. pusilla Col. is illustrated for the first time.

Abstract: The ecology of Alseuosmia quercifolia, a small endemic shrub, was investigated, focussing on its habitat requirements, population dynamics, phenology and reproductive biology, and conservation status. This species occurs most commonly in lowland native forests of the Waikato region of the North Island (north of latitude 38°05'S), but is also found in scattered populations to North Cape. In the Waikato region it typically occupies shady, well‐drained, south or south‐east facing lower slopes of hills and ranges at altitudes below 400 m. Population structures show considerable variation amongst seven study sites in the Waikato region, with disjunct size classes a reflection of the presence and abundance of introduced browsing mammals. It is a relatively short‐lived (less than 50 years), slow‐growing species with a fleshy fruit adapted to bird dispersal, but seed dispersal now appears to be primarily by gravity. Flowering occurs early in spring and is synchronous at both individual and population lev...

Abstract: The flowering plant family Alseuosmiaceae comprises three genera of shrubs: Alseuosmia A. Cunn. from New Zealand; Memecylanthus Gilg and Schltr. and Periomphale Baill. (=Pachydiscus Gilg and Schltr.) from New Caledonia. These genera are readily excluded from their traditional position in the Caprifoliaceae by virtue of their alternate leaves, valvate corolla lobes and their southern hemisphere distribution. Four species of Alseuosmia, including one hitherto undescribed species, are accepted here. The New Caledonian genera are poorly represented in herbaria; they may each be monotypic. Condensed tannin (leucocyanidin) and ellagitannin are abundant in all Alseuosmia tissues. Other simple phenolic compounds here (as detected in acid hydrolysates) include quercetin, kaempferol, caffeic acid and p-coumaric acid. Triterpenoid saponins are abundant in leaf tissue; alkaloids and probably iridoid compounds too, are absent. Tannin is found throughout the ovary tissue of Alseuosmia and in the inner and outer epidermises of the ovular integument. The floral vascular anatomy is detailed for the Alseuosmiaceae and reviewed for eight allied families. No features of the vascular system imply particular affinity of the Alseuosmiaceae with any of these allies. Within this family the association of different morphological and anatomical floral features supports the contention that primitive characters tend to be associated with one another in their distribution throughout the members of a taxon. The primary vascular pattern in the stem of Alseuosmia is of an open (sympodial) nature. The mature nodal anatomy is 3-trace trilacunar. All genera have a stem endodermis with prominent Casparian banding, and in Alseuosmia at least this endodermis passes through the secondary and quaternary stages (lignification-suberisation of walls; accumulation of phenolic compounds) as found in a typical root endodermis. All species of Alseuosmia lack rays in the secondary wood, whereas memecylanthus and Periomphale have extremely tall (indefinitely-prolonged?) rays. The vessels of these genera are relatively primitive (end-plate angle c.10-19??, no bars per scalariform plate c.16-37), and thus are comparable to vessels of the Escalloniaceae and Caprifoliaceae. The root periderm has a cortical origin in Alseuosmia and the root pith is persistent. Multicellular uniseriate hairs are found in the leaf axils in all Alseuosmiaceae. Hairs with similar structure and development are found in some genera of Pittosporaceae but not, so far as is known, in other related groups. Within Pittosporum, these uniseriate hairs appear to be homologous with the T-hairs many species have. The chromosome number of 2n=18 probably characterises all the species of Alseuosmia. A. macrophylla A. Cunn. is an obligate outbreeder with an incompatibility mechanism operating at the stylar level, while A. pusilla is self-compatible. Pollinating agents for the species are unknown. No internal barriers to hybridism exist between A. macrophylla and A. banksii A. Cunn. and the hybrid swarm…