SLIDE 1 MONOTOCA SCOPARIA
TWO FRUITS
Betsy R. Jackes
James Cook University
Peter G. Kevan
University of Guelph
SLIDE 2 MONOTOCA SCOPARIA
- Subfamily Styphelioideae, family Ericaceae
- Shrubs to 1.3 m tall, lignotuber present
- Inflorescence axillary, few-flowered spikes
- ften clustered
- Functionally dioecious or ?
- Ovary 1-locular
- Fruit a drupe, yellow to orange
SLIDE 3
OBSERVATION ALL REPRODUCTIVE PLANTS NEAR PALUMA PRODUCED FRUITS. MAIN QUESTION IS MONOTOCA SCOPARIA GYNODIOECIOUS, FUNCTIONALLY DIOECIOUS OR?
SLIDE 4 Townsville Wet Tropics bioregion
Where are we?
BRISBANE
Queensland
SLIDE 5
SLIDE 6 STUDY SITES
- THREE POPULATIONS ALONG A DECREASING
RAINFALL GRADIENT
- QUADRAT 30 X 18 M
- ALL PLANTS AT EACH SITE SEXED AND TAGGED AND
CO-ORDINATES RECORDED
- ARE SEXES RANDOMLY DISTRIBUTED OR NOT?
SLIDE 7
Site 1 19o 00’ 27.8”S 146o 05’ 31.3”E
SLIDE 8
Distribution Site 1
SLIDE 9
Site 2 19o 00’ 08.1”S 146o 04’ 48.7”E
SLIDE 10
Distribution Site 2
SLIDE 11
Site 3 18o 59’ 59.5”S 146o 04’ 29.5”E
SLIDE 12
FEMALE PLANTS (WITH STAMINODES) MALE PLANTS (WITH FERTILE STAMENS) WERE RANDOMLY DISTRIBUTED AT ALL SITES DESPITE VARIATIONS IN TOPOGRAPHY AND MOISTURE LEVELS
SLIDE 13
IS THERE A DIFFERENCE IN THE NUMBER OF FLOWERS PRODUCED PER SEX? For each sex, 10 plants tagged, 10 sprigs per plant tagged, each sprig 10 cm long, all flowers counted Female mean 1381, SD 196 Male mean 1295, SD 240 No significant difference
SLIDE 14 No significant difference
Female sprigs Male sprigs
SLIDE 15 ♀ Male flower, c. 2.1 mm long Female flower c. 1.5 mm long
SLIDE 16
DO MALE AND FEMALE PRODUCE EQUAL QUANTITIES OF NECTAR? Sprigs cut and placed in water, covered with a plastic bag, left overnight Then checked under a dissecting microscope and scored for the amount of nectar present.
SLIDE 17 1 = brim full 2 = well above ovary but not overtopping the style 3 = visible sparkle at base
4 = no visible nectar
SLIDE 18
NECTAR RESULTS
Female n=150 Male, n= 192 1 (none visible) 56 2 49 2 3 32 72 4 (brim full) 13 96 Female flowers produced significantly more nectar than male flowers
SLIDE 19
POLLEN
Pollen from 10 plants, 4 flowers per plant Stained with Alexander’s Stain – grains unstained or partially stained and irregular in shape recorded as aborted. Pollen grains per flower ranged from 2437 to 13375 mean 8762 % fertility or non-aborted grains = 81.9%
SLIDE 20 TWO FRUITS
firmly attached to parent globular to pear-shaped 2.4-2.7 mm long, 2.1-2.4 mm wide
weakly attached to parent cylindrical 2.5-3 mm long, 1.25-1.5 mm wide
SLIDE 21
Female plant
SLIDE 22
Female, mature and maturing
SLIDE 23
Male, mature and maturing
SLIDE 24 FRUIT SET
- All fruit present on the tagged plants were
collected after 2 months.
- Percentage fruit set based on the number of
buds and flowers recorded for each plant.
- Combined data for sites 1 and 2
Female 27.11% Male 11.41%
SLIDE 26 Presence or absence of a well-developed embryo
- Fruits collected from both sites 1 and 2
- Method 1: Fruits cut in half and nature of the
embryo noted microscopically, n=20
- Method 2: Fruits cleared with methyl
salicylate (modified from Stelly et al. and Scriballo & Barrett). All questionable results confirmed by sectioning
SLIDE 27
Site # examined #well-developed embryos female 1 154 87 2 296 142 450 229 male 1 327 2 216 0 (2 partial) 543
Note: No females without partially developed embryos
SLIDE 28 ‘female’ seeds with endocarp
2.1-2.5 mm long, 1.2-1.5 mm wide
SLIDE 29 FLORAL VISITORS
- 20 plants, 10 of each sex, 4 sweeps per plant
- All insects captured and examined for pollen
load
- Only Trigona ?carbonaria carried Monotoca
pollen.
- Male plants, 21 bees captured
- 10 with pollen, 11 lacking pollen
- Female plants, 23 bees captured
- 7 with pollen, 16 lacking pollen
SLIDE 30 CONCLUSIONS
- Monotoca scoparia is functionally dioecious, sexes
are randomly distributed
- Two fruits develop but no viable embryos in ‘male’
fruit
- Flowers differ in size and shape with sex
- Female flowers produce considerably more nectar
than male flowers
- Trigona ? carbonaria is the pollinator
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