June Tree Talk: Trees and Bees

During the recent BioBlitz hosted and sponsored by Capital Trees, tables were set up under the shade of the ample cottonwood tree at Great Shiplock Park. Cyclists and walkers alike waded through the cottony masses that settled onto the ground after each breeze. The cottonwood tree, a type of poplar, is pollinated by the wind carrying pollen from the male flowers to the female ovules. Insects, such as bees can help the process by carrying pollen from one tree to the next. 

In fact, about 80% of flowering plants and trees are pollinated by critters. Most of these critters are insects and most of these insects are bees. It is not a surprise that bees co-evolved with flowering plants. Think about it: trees and flowers produce nectar and pollen to attract bees, birds, and other animals to assist in pollination. Pollination occurs when pollen is transported from the anther to the stigma of the same flower or another flower of the same species. In order to become fertilized, the pollen (male) on the stigma travels down the style to the ovary, where it connects with the egg (female) to form an ovule, which matures into a seed. 

This co-evolution of bees and flowering plants is one of the many wonders of nature. In February through early March, when you see willow and maple trees flowering, honeybees are raising brood to increase the population of the colony and there are a lot of larvae to feed. As field bees pollinate flowering plants, inevitably, some of this pollen is carried back to the colony. Nurse bees consume the pollen and mix it with enzymes from their hypopharyngeal glands (glands in their head) to produce ‘royal jelly’, which is used to feed all larvae for the first three days with an average feeding time of every 43 seconds. Larvae that workers want to develop into queens continue to be fed royal jelly throughout their development. After being fed royal jelly initially, workers and drones transition to ‘worker jelly’ (bee bread), which is a mixture of royal jelly, pollen and nectar. A lot of pollen is needed since the queen can lay over 2,000 eggs per day! 

The co-evolution continues in mid-March with the blooming of Oak and Redbud trees followed by a continuous supply of Cherry, Black Locust, Tulip Poplar, Blackberry & Raspberry and other fruiting trees in April and May. Basswood (Linden) and Sourwood blooms close behind in June and July with fall trees such as Sweet Autumn Clematis, American Holly and other fall flowering plants rounding out the package.

In addition to pollen, nectar from trees is also important for the development of honeybees. Honeybees gather nectar through their proboscis (tongue, which can be used like a straw and pipet) and then transfer this energy source (carbohydrates) to waiting bees in the colony. These ‘house bees’ will convert the nectar into honey to be used for food. 

Additionally, honeybees also collect sap from trees and mix it with their saliva to create propolis, a sticky resin-like substance that is used much like glue to seal small spaces. By doing so, honeybees can control the temperature inside the colony and protect the colony from unwanted pests. Propolis is antibacterial and antifungal, and has all sorts of homeopathic uses, as does pollen and honey. 

Trees like the cottonwood are not just beautiful, they are important to pollinators and pollinators are important for them as well. It is a nice reminder that we are all connected: tree, insect, people. 

In community, 

Hollee Freeman, PhD

June — Urban Green Space Maintenance

Summer is officially here, and with the recent heat wave, its arrival has been anything but subtle. Though the extreme heat presents challenges, there is always work that still needs to be done in the gardens. This month we planted some native grasses at the Low Line Green and did some cutbacks to the Baptisia australis and the Amsonia hubrichtii along the Low Line. As always, the garden weeds don’t take breaks. We have continued to focus weekly efforts on tackling the summer annual weeds that are thriving in the long hot days.

June — Featured Trees Seasonal Update

This year we’ll be documenting the same two trees as they progress out of dormancy, bud out in the spring, are full of foliage in the summer, and lose their leaves in the fall. Follow along for monthly updates on the River Birch and Eastern White Redbud along the Low Line Gardens in Richmond, Virginia.

June — Spotted at Low Line Gardens

If you have been to Great Shiplock Park in the last month you might have noticed that it looks like a winter wonderland. No no, we haven’t gotten snow – the Cottonwood trees are dropping their seeds! The seeds are delicate white fluffs, and if you catch them on the right day it can create the appearance of a summer snow.