Floral structure and development in the dioecious Australian endemic Lomandra longifolia (Lomandraceae)

Abstract

The micromorphology and histology of the development of male and female flowers of the dioecious Australian endemic species Lomandra longifolia Labill. was studied by means of scanning electron microscopy and light microscopy of entire and sectioned material. Although mature flowers are functionally unisexual, in the early stages of development pistillate and staminate flowers are identical and apparently bisexual. In a sequential fashion, six perianth parts are initiated within two alternating whorls, the sepals first and the petals second; six stamens are initiated in two alternating whorls of three stamens each, the first opposite the sepals and the second opposite the petals; and last, a central gynoecium is initiated. Following initiation, the two flower types diverge developmentally when the stamens become bilobed. In male flowers, cytological analysis of the slowly growing abortive pistil shows that megasporogenesis does not occur. Pistil abortion happens before meiosis whereas the stamens continue to develop until maturity and dehiscence. In female flowers, stamen arrest occurs before the onset of meiosis in microspore mother cells, after which the pistil continues its development through megasporogenesis and megagametogenesis. In all, 14 stages of floral development of both male and female flowers have been designated. Stages 1–6 of the two flower types were common to both sexes.

Patterns of plant species composition in mesic woodlands are related to a naturally occurring depth-to-groundwater gradient

“…High abundances of bracken fern (Pteridium esculentum) and the rush Lomandra longifolia at deep sites indicate that these understorey species are tolerant of dry conditions (Ahmad et al 2009, ANBG 2012. It is not surprising that a species such as bracken fern is one of the dominant species at the deep sites, as it is an unusual fern that has a high degree of stomatal control of transpiration (Pitman 1989).…”

Patterns of angiospermy development before carpel sealing across living angiosperms: diversity, and morphological and systematic aspects

“…Asparagales‐Asparagaceae , Lomandra longifolia Labill. (Ahmad, Martin & Vella, , figs 45, 47). Asphodelaceae ( Xanthorrhoeaceae) , Asphodeline lutea (L.) Rchb.…”

Clonal propagation of Lomandra longifolia by somatic embryogenesis

“…Immature inflorescences and immature ovaries can be prolific sources of explants to multiply desirable genotypes (Ahmad et al, 2008). However, in our experiments there was a high incidence of contamination when we attempted to use these plant parts, especially with samples taken from field-grown plants.…”

“…Leaf bases, immature inflorescences, and immature ovaries from the tillers of a field selected elite genotype (voucher specimen of the elite genotype has been deposited in the Australian National Herbarium CANB 763118). Tiller bases (≈5.0 cm long), immature inflorescences (harvested when the inflorescence is approximately 7.0 cm in length with about 2.0 cm being visible above the leaf bases), and immature ovaries (collected about one week before flower anthesis, equivalent to stage number 13 as reported by Ahmad et al (2008)) were excised and surface sterilized by immersion in 50% bleach (4.5% sodium hypochlorite) with 0.1% Tween-20 for 15 min, followed by 3x rinsing with sterile distilled water in a laminar flow hood. The tiller bases were then longitudinally sectioned and individual leaf bases 2-3 cm in length were cultured, whereas young inflorescences were cut into segments 0.5-1.0 cm long.…”

“…longifolia is usually propagated by seed. As a cross-pollinated dioecious species (Ahmad et al, 2008), it does not breed true to type and therefore, sexual propagation does not ensure that favourable genotypes (outstanding selections) are passed on to the next generation. In comparison, clonal propagation in outcrossing plants helps to preserve heterozygous genotypes that show hybrid vigour and enables retention of plants producing gametophytes of one gender only and to maintain cultivar identity.…”