Grevillae+D&H

Grevillea By Daniel Stang and Hayden Speer

Plant Species: //Grevillea spp// Plant Family: Proteaceae Common names: Toothbrush, Silky-oak, Spider Flower, Bottle Brush Distribution: South America, South Africa, New Zealand and Australia (the continents that made up Gondwana) Thrives in sandy or rocky soil with low levels of phosphorus Source: Bove, F., (2012) //In Bloom: Grevillea spp.// Retrieved from: [] Habit: Can range from up to 30 m tall trees to as low as 20 cm for ground covering species Flowers: most have small, slender curved flowers, with a range of colours Fruit: large range, generally a woody and hard exterior

Grevillea preissii spp. glabrilimbra - 'Spider-net Grevillea' Image from []


 * Floral Morphology**

//Figure 1: structure of a typical Grevillea flower//

Floral structures of the //Grevillea spp.// samples were measured using calipers. The following values were obtained from a sample of three flower spikes. Average style length: 4.78 cm Average number of flowers per inflorescence: 100 Average diameter of flower spike: 9.7 cm Average height of flower spike: 10.5 cm  Average volume occupied by flower spike: 802.8 cm^3
 * Variability of Floral Morphology **

**Pollen Morphology**



This image was obtained under 100 x zoom. The scale is such that 1 cm = 3 µm. The pollen grains present as being small and of a triangular shape. Each flower produces a substantial amount of pollen. The pollen tube grows out of the corner of the pollen grain until it comes in contact with the stigma to begin the fertilization process.

**Nectar Characterization**

 Nectar was collected from the flowers through the use of a number of 10µL tubes. These were then emptied onto the surface of a refractometer until they were completely covered, which allowed the sugar content of the nectar to be measured. The results showed that the nectar in the //Grevillea //flowers contained 17.3% sugar. However, there was a large range of nectar obtained ( 0.5µL-6µL),. This may suggest that the //Grevillea // is selective about where it places its nectar, with the purpose of maximizing pollination through surface contact with its vectors.