Wednesday, April 13, 2016

Pawpaw Flowers

Pawpaw flowers in full bloom - REK
This is the time of year we start monitoring the pawpaw flowers.  Sudden freezes turn them into shriveled dark brown blobs, robbing them of the chance to make fruit.  It is a miracle that we ever have any pawpaw trees, let alone fruit.  Their fruits are popular with squirrels, raccoons, and bears.  In season we see bear scat filled with seeds, the pawpaws transportation out of the neighborhood.  Since their fruit are challenged by late frost, this method of propagation is hazardous.

Pawpaw flowers, fresh, dead and frost damaged - REK
Pawpaw, (Asimina triloba) have several survival techniques.  Their main method is to reproduce by suckers, roots extending out to establish trees nearby in an expanding community.  Left alone they could cover a large area but as a forest matures over years around them, their expansion is controlled.

Like other species producing dark brown to purple flowers, they rely on a smell of rotting flesh to attract pollinators, not butterflies but flies and other species attracted to the odor of death.*  Their flowers meanwhile are pollinated in a hit and miss fashion by flies, beetles and other species.  In some limited attempts to grow pawpaw commercially, growers actually hang dead fish and other lures to attract these morbid pollinators to their trees.

Bud ready to flower
We have noticed over the years that the flower blossoms develop and open up sequentially over 4-6 weeks in the spring.  Currently we have dried shriveled flowers killed by frost 3 weeks ago as well as recently stunted blossoms from the freeze a few days ago.  On the same tree are unopened buds both ready to open next to tiny emerging flower buds, the whole spectrum on a single tree.

Fresh flower and small new flower bud - REK

The early blooming pawpaw has thus found a way with dealing with these setbacks by spreading its flower buds over more than a month.  While observing this budding over time, we haven't noticed whether it ends when the frosts stop.  It is possible that this continuing flower bud propagation is the plant's response to frost damage.

*Further information on Pawpaw odors is in this paper.
Previous pawpaw blogs have covered Zebra Swallowtail eggs, the  butterfly's premature delivery and the Asimina webworm moth that lives curled up in pawpaw leaves.

1 comment:

  1. Very nice analysis, augmented with lovely images