Getting More Fruits

Sassafras blooms in the first part of spring. 
This photo was taken on April 12th.

I have been planting more native trees and shrubs with the goal of increasing the amount of food available for birds.  Particularly fruits that are available in fall and winter.  In many cases these plants are dioecious. That is, an individual plant of the species is either male or female.  To get berries you need at least one male to fertilize the female flowers.  Sometimes getting male and female plants is easier when you are buying cultivars.  It is often documented somewhere (but not always) if a cultivar is male or female.  When buying seed-grown natives it is difficult to tell unless they happen to be in bloom when you are shopping.  If plants are not in bloom the recommended approach is to get 5 random plants so that there will be a good chance that you will get at least one of each.

This year I have spotted some firsts in my campaign to produce more native berries.  The first success that I noted was that my newly planted sassafras tree, Sassafras albidum, was a female [note structure of female flower].  There is a number of wild sassafras in the area, but the flowers are way up in the tree so I have not been able to distinguish their gender.  About a month after blooming I noted that there were a couple of berries forming.  They are green right now, but will turn dark blue when ripe.

Female flowers have 6 sterile stamen (staminodia) surrounding
a central pistil.  Male flowers have 9 stamen.

Here at the beginning of July you can see the green berries.  When ripe these berries
will turn dark blue and the pedicels will turn red.

The second species I spotted with fruit forming was persimmon, Diospyros virginiana.  There has been male tree on the property for some time.  I don’t know if it’s wild or was planted by the previous owners.  When I moved 7 years ago I planted a number of native persimmons all of unknown gender.  To improve the chances that I had at least one female I planted 6 new plants.  Last year one of them bloomed that proved to be a male.  This year two additional trees bloomed, both of which were female.  Shortly after the flower petals fell off I noticed that two of the female flowers had swollen ovaries.  Now I can hope that they survive long enough to ripen.  I may need to build a little fence around them to keep the deer away.  

Female flowers are usually solitary and have 8 sterile anthers around the pistil.
 On male trees flowers are clustered and are typically packed with 16 anthers.

About a month later this persimmon is developing. 
Green now it will turn orange when it ripens in the fall.

Another recently planted native tree that is now showing some berries is fringe tree, Chionanthus virginicus.  Fortunately these bloomed the second year after planting.  The first three of these I planted either appeared to be females or had not bloomed after two years.  The following year in early June I was in a native plant nursery when these were in bloom.   I was able to identify one specimen as a male (paddle-shaped anthers in throat of flower) and bring it home for the girls.  Now 4 years later I’ve spotted the first berries on the fringe trees.  Like with the sassafras these start out green then turn dark blue when ripe. 

This green berry on the fringe tree will turn dark blue when it ripens in early fall.

Two years ago I replaced some invasive leatherleaf mahonia, Mahonia bealii, with some inkberries, Ilex glabra.  I wasn’t able to get a male cultivar locally.  I found a suggestion on the internet that other hollies could fertilize inkberries.  To try this I planted an early blooming winterberry holly, Ilex verticillata ‘Jim Dandy’ nearby.  After planting my collection of inkberries including the ‘Nigra’ and ‘Shamrock’ cultivars I took a close look at the flowers.  While the flowers on ‘Nigra’ were exclusively female, ‘Shamrock’ appeared to have both male and female flowers.  Unfortunately this year I forgot to take a close look at these flowers to confirm my earlier observations.  I can say that this year I am seeing a lot of berries developing on the ‘Nigra’ plants, as well as on a single wild-type plant.  The ‘Shamrock’ cultivars bloomed this year but are lacking berries.  They had a lot of berries in their first year here.  

This female flower has a large central ovary surrounded by six sterile stamen. 
In male flowers these stamen will have yellow pollen on the anthers.

Also on the holly front, this year I added another winterberry holly, ‘Winterred.’  This is a later blooming female.  Its blooming cycle is perfectly timed with the male, ‘Southern Gentleman.’  While it was still in its pot I placed the ‘Winterred’ next to the ‘Southern Gentleman’ until the blooming period was nearly completed.  This should ensure some berries as long as it doesn’t get stressed too much from being planted out in late June.

Some other species that are not dioecious have mechanisms that encourage cross pollination. This ranges from clever flower construction that prevents self-pollination, to offset timing of pollen release and receptivity, to outright rejection of pollen with the same genetic material as the ovary.  To encourage fruit and seed production you should have at least two genetically distinct individuals within pollination range. 

This is what I’m thinking about my single American plum, Prunus americana.   Despite several years of impressive blooming I have not seen any fruits on this tree.  I don’t know how long these need to mature before they are ready to bear fruit.  To help with cross pollination I’ve planted several bare root American plums in the area but I think it will be a few more years before these begin to bloom.

Another fruit-bearing native that has appeared on my property is black raspberry.  I’d like to think that these have been encouraged by the removal/reduction of invasives like Japanese stiltgrass, wineberry and garlic mustard.

Black raspberry has round stems and first year canes are glaucous. 
Flowering occurs in mid-May

The black fruits ripen around the end of June and have a distinctive sweet flavor. 
These ripen a week or two before the wild blackberries, which are much tarter.