MONOTOCA SCOPARIA TWO FRUITS Betsy R. Jackes James Cook University Peter G. Kevan University of Guelph
MONOTOCA SCOPARIA Subfamily Styphelioideae, family Ericaceae Shrubs to 1.3 m tall, lignotuber present Inflorescence axillary, few-flowered spikes often clustered Functionally dioecious or ? Ovary 1-locular Fruit a drupe, yellow to orange
OBSERVATION ALL REPRODUCTIVE PLANTS NEAR PALUMA PRODUCED FRUITS. MAIN QUESTION IS MONOTOCA SCOPARIA GYNODIOECIOUS, FUNCTIONALLY DIOECIOUS OR?
Townsville Wet Tropics bioregion Where are we? BRISBANE Queensland
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?
Site 1 19 o 00’ 27.8”S 146 o 05’ 31.3”E
Distribution Site 1
Site 2 19 o 00’ 08.1”S 146 o 04’ 48.7”E
Distribution Site 2
Site 3 18 o 59’ 59.5”S 146 o 04’ 29.5”E
FEMALE PLANTS (WITH STAMINODES) MALE PLANTS (WITH FERTILE STAMENS) WERE RANDOMLY DISTRIBUTED AT ALL SITES DESPITE VARIATIONS IN TOPOGRAPHY AND MOISTURE LEVELS
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 Femalemean 1381, SD 196 Malemean 1295, SD 240 No significant difference
Female sprigsMale sprigs
♀ Male flower, c. 2.1 mm long Female flower c. 1.5 mm long
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.
1 = brim full 2 = well above ovary but not overtopping the style 3 = visible sparkle at base of corolla tube 4 = no visible nectar
NECTAR RESULTS Female n=150Male, n= (none visible) (brim full) 1396 Female flowers produced significantly more nectar than male flowers
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 mean 8762 % fertility or non-aborted grains = 81.9%
TWO FRUITS Fruit from female plant firmly attached to parent globular to pear-shaped mm long, mm wide Fruit from male plant weakly attached to parent cylindrical mm long, mm wide
Female plant
Female, mature and maturing
Male, mature and maturing
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 Female27.11% Male11.41%
‘female’ ‘male’
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 Method 3: squishing
SexSite# examined #well-developed embryos female male (2 partial) 5430 Note: No females without partially developed embryos
‘female’ seeds with endocarp mm long, mm wide
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
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