When we first visit the woodland we want to see flowers. Flowers however are not produced to decorate the woodland for us humans, but are the sexual organs of the plant and the initial stage in the reproduction of the plant. The flower’s purpose is to enable the pollination process to take place. Following pollination the flower develops into the fruit and seeds.
Most of our woodland plants have male organs (stamens and anthers with pollen) and female organs (stigma and ovaries) in the same flower (bisexual) on the same plant (monoecious). A few species produce separate male and female flowers (unisexual) on different plants (dioecious), e.g. Asperula conferta, Clematis glycinoides, Lomandra multiflora, Lomandra filiformis. In small populations of dioecious species where there are few or even no plants of one sex, there may be inadequate pollination and failure to set seed. For example in the woodland at the Australian Botanic Garden there is only a very small population of Lomandra multiflora.
Many plant families have very distinctive flower types - the family Fabaceae has pea-shaped flowers e.g. Lotus australis, while the grass and sedge families have specialised flowers that you might hardly recognise as flowers e.g. Scleria mackaviensis.
For most native woodland species flowering is not tied to particular seasons but is dependent on adequate rainfall and may happen at any time. This is in contrast to the plants in the Sandstone woodlands of coastal Sydney which have a distinctive peak of flowering in spring (September-October).
Unlike the colourful Banksias and Waratahs of the sandstone areas, most of the woodland flowers are small and not colourful. Flower colours are predominantly white, with some pink, purple or yellow. Colour and shape relate to pollination modes.
In contrast to the native species, many of the exotic weed species that are naturalised in the woodland have conspicuous and colourful flowers e.g. *Heliotropium amplexicaule, *Verbena rigida, *Hypericum perforatum, as many of these were introduced to Australia as garden plants, and have subsequently escaped from cultivation.
Flower opening times
While we are used to seeing the flowers of most cultivated garden ornamental plants remaining open all day, there are different daily flower opening times for some of the woodland species. The flowers of some species remain open all day and under all conditions e.g. Bursaria spinosa, Pimelea spicata, Indigofera australis. Other species have flowers that are only open when it is sunny, and even then, for only part of the day e.g. Caesia parviflora and Wahlenbergia gracilis are open in the afternoons, Hypoxis hygrometrica and Tricoryne elatior are often open in the morning. On very hot days most flowers tend to wilt e.g. Ajuga australis.
Flowers of some species may last a few days, but others are only open for a day e.g. Caesia parviflora, although the plant may produce a succession of flowers. Flower availability is likely to be important in pollination, and presumably the period and time of opening relates to the presence of pollinators. However we know very little about the native pollinators of the woodland species.
Some plants do not produce flowers. Ferns produce spores which grow into prothalli on which the next generation embryo grows. Of the four fern species in the woodland, two are confined to moist habitats but the other two Cheilanthes sieberi and Cheilanthes distans grow in the dry woodland similarly to the other ground species.
Asterisk * indicates exotic species naturalised at the Australian Botanic Garden.