Bolwarra or native guava

Article and images by Michael Mills, community conservation officer

In November, the Alex Forest conservation area was alive with the unmistakable scent of the bolwarra/copper laurel/native guava (Eupomatia laurina). The BushCare group who care for this reserve, meeting on the first Saturday of the month, witnessed the first flowers to open, with dozens if not hundreds more buds about to open. This was incredibly lucky as individual flowers generally last only 24-48 hours after opening. Over the course of the next week the rest of the flowers opened, with many already turning to unripe fruit under a week after the flowering commenced.

Integral to this process are weevils of the Elleschodes genus. Each flower has male and female “parts” that open at different points in the day, male in the evening and female in the morning. When each part opens they exude a very sweet and floral smell from the staminodes housed within the flower. This scent attracts the weevils, who may visit multiple flowers during this time, feeding on the staminodes and whilst doing so collect pollen. When the female parts open in the morning, the floral scent is again released drawing the weevils to feed on staminodes, they now transfer the collected pollen to the stigma. With the gap in time between male and female parts of the flower opening it increases the chance weevils will visit multiple flowers overnight and then be drawn to a different flower come morning when the scent is released again. This allows for good genetic diversity of a population. If all of that sounds like a complicated process, that’s because it is; this is a primitive way for plants to reproduce and most flora reliant on flowering and pollination have developed much more simple mechanisms for reproducing and can be pollinated by a variety of species.

Weevils of the Elleschodes genus are obligate pollinators for the bolwarra, it is considered a relict plant due to its reliance on this single genus of weevil. If this genera of weevils experience a significant decline, say due to increased use of pesticides or environmental conditions deteriorate due to global warming, the bolwarra could eventually become extinct. Consider then that this family of plants (Eupomateacae) separated from their closest relatives 80-120 million years ago and have retained this association with the Elleschodes weevils. These plants and their weevil pollinators are a link to another time and are still thriving today, and hopefully will continue to persist long into our future.

Visit the BushCare Sunshine Coast website to find out how you can get involved with the Alex Forest Preservation Group or other local BushCare groups.