Bottlebrush

Group members: Aidan, Annie, Danya and Michael = = =Plant Species: **//Callistemon citrinus//**=
 * Plant Family:** Myrtaceae
 * Common name**: Crimson or Red Bottlebrush
 * Distribution:** East and South-east of Australia / New South Wales, Victoria and southern Queensland

Figure 1: Distribution of //Callistemon citrinus// in Australia. (Source: Atlas of Living Australia (2012) (accessed at: http://bie.ala.org.au/species/Callistemon+citrinus))

**Soil conditions / Habitat**: Usually found in wet or swampy conditions. Prefers well-drained soil including sandy, loamy and clay soils. Acid and neutral soils. Requires sunlight light and can tolerate drought. (Source: (Curtis.)Skeels. Plants For a Future. 2012. Accessed at: http://www.pfaf.org/user/Plant.aspxLatinName=Callistemon+citrinus)
 * Growth:** Can grow to be 2m x 2m

Figures 2 and 3: //Callistemon citrinus// flowers and buds.

**Flowers**: small, red. Unlike other plants which have vibrant coloured petals, the stamens on this plant are red and most prominent to attract pollinators such as birds and small mammals.
 * Inflorescence:** a cluster of small flowers arranged linearly along and around branch

The flowers - precisely the filament and styles - are a vibrant red colour. The male and female reproductive structures are prominent, contained in a cup-like, nectar containing structure surrounded by relatively small, unobtrusive petals. The flowers are fairly densely arranged. (Source: Bottlebrush - genus //Calllistemon.// Australian National Botanic Gardens. Accessed at: http://www.anbg.gov.au/callistemon/index.html)
 * Fruit:** Each flower produces small woody fruit which contains hundreds of small seeds

Figure 4: Single //Callistemon citrinus// flower and calipers (measuring 13mm).

__Floral Morphology__
Figure 5: Labelled image of single //Callistemon citrinus// flower.

__**Floral Measurements**__
Number of stamen: Counting on each flower Floral structure length (stamen, carpel): Used calipers Potential sources of error: Difficult to measure the three-dimensional structures of flower and difficult to measure the distance between male and female structures. Pollen morphology: Dissected anther to remove pollen and stained with fuchsin gelatin. This was viewed using a light microscope. Nectar characterisation: Glass capillary tube was used to extract the nectar (10uL capillary tube). The refractometer was used to measure the sugar content of extracted nectar. **Table 1: Sample Findings** Out of a sample of 5 flowers: Average number of stamens counted: 36. Stamen and carpel are approximately the same length: 15mm. Stamen and carpel are situated close to each other. The anthers and stigmas fluoresce under UV light => signal for pollinators. The stamen length ranged from 7.6 to 15.4mm - average: 14.7mm The carpel length ranged from 11.2-16.6mm Also by visual assessment the carpels appear slightly taller than the stamens on average. Volume of nectar: 8.6microlitres Pollen Shape: triangular
 * How measurements were conducted:**
 * Specimen no. || 1 || 2 || 3 || 4 || 5 || Average ||
 * Number of Stamen || 38 || 39 || 39 || 40 || 33 || 37.8 ||
 * Longest Stamen Length in Flower (mm) || 13.7 || 13.7 || 15.9 || 12.5 || 15.1 || 14.18 ||
 * Shortest Stamen Length in Flower (mm) || 8.3 || 7.6 || 8.3 || 11.5 || 8.3 || 8.8 ||
 * Carpel Length (mm) || 11.2 || 13.4 || 14.4 || 13.7 || 16.6 || 13.86 ||
 * Reproductive structures:**
 * Sugar content of Nectar : 14.7% of nectar**

Figure 6: Pollen Grains of //Callistemon citrinus.// The flowers are bisexual (contain both female and male organs). The stamen and carpel are closely located, with each flower containing about 25 stamens (filaments with anthers) with a central carpel (stigma and style).

Figure 7: Cross section of flower showing female reproductive organs. Figure 8: Flowers under UV light showing anthers fluoresce. Figure 9: Cluster of //Callistemon citrinus// flowers.
 * Table 2: Features and Implications.**
 * FEATURE || IMPLIED POLLINATOR ||
 * Small flower size || Insect ||
 * Nectar || Insects, birds (honey eaters) ||
 * Nectar is located inside small narrow cups || Birds with narrow beaks, small insects ||
 * Vibrant red colour || Insects and birds nb. bees don't see red ||
 * UV fluorescence || Seen by insects ||