Witch Hazel Capsules Few And Far Between
The deciduous shrub Witch Hazel (Hamamelis virginiana) flowers in the fall as its leaves are dropping, when night temperatures often fall below freezing. This autumn-flowering period is strikingly different than that of most other flowering shrubs, which flower from very early spring to early summer. This unusual timing creates a combination of factors such as more severe weather and fewer pollinators that make fertilization and fruit-setting challenging.
Pollen transfer (primarily by bees and flies still flying in cool weather) occurs during the flowering period in the autumn, but fertilization does not occur until the following spring, around the time new leaves are produced. The percentage of flowers that actually set fruit is extremely low – less than 1% in a study of 40,000 flowers.
Approximately 80% of Witch Hazel flowers fall off the plants by December. Roughly 8% of the initial flowers remain on the shrub by March of the following spring, when fertilization takes place. From 72% to 90% of the fruits/flowers on the plants in March are lost before early July. Those few capsules that remain on the shrub continue to develop through the growing season, reach maturity in late August, and remain on the plant even after the next year’s flowering commences (see photo). The two seeds within each capsule are forcibly ejected as far as 30 feet when the capsule dries and splits open.
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Witch Hazel Flowering & Dispersing Seeds
Long after most bird songs have ceased, summer’s flowers have turned to seed, and leaves are starting to fall, a woodland shrub, Witch Hazel, Hamamelis virginiana, brightens the landscape with its tiny, golden blossoms. At this exact same time, Witch Hazel flowers that were pollinated a year ago and fertilized this past spring have developed capsules that are dispersing two black seeds, shooting them up to thirty feet away from the parent plant, making audible popping sounds as they open and eject the seeds. This dual-purpose timing of both flowering and seed dispersal is a feast for both eyes and ears every autumn for those fortunate enough to locate a shrub and time their visit perfectly.
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Witch Hazel Pollinators
October through mid-November is the typical flowering time for Witch Hazel. The last of the blossoms of this fall-blooming shrub can still be seen in parts of the Northeast. Its long, bright-yellow petals and the presence of a sweet-smelling nectar tell you that Witch Hazel flowers are pollinated by insects. However, there are very few insects present this late in the year and its pollinators have been elusive to the human eye. With the exception of syrphid, or hover, flies, I have never seen any insects visiting these flowers.
It turns out that I was observing them at the wrong time of day. Naturalist Bernd Heinrich discovered that a group of owlet moths called winter moths are active on cold nights and regularly visit Witch Hazel. These moths have the ability to heat themselves by using energy to shiver, raising their body temperatures by as much as 50 degrees in order to fly in search of food. Solved is the mystery of what pollinating insects are still active this late in the year!
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Witch-hazel Cone Gall Aphids Laying Eggs
At this time of year there is a species of aphid, Hormaphis hamamelidis, that is laying eggs on Witch-hazel branches. Next spring female aphids will hatch out of these eggs and begin feeding on newly-emerged Witch-hazel leaves. The aphids inject the leaf with a substance that causes the leaf to form a cone-shaped growth, or gall, around the insect, providing it with both food and shelter. The galls are hollow, and have openings extending out through the leaves’ lower surfaces. Within the galls the unmated female aphids produce 50 – 70 young. Eventually the galls fill with winged female aphids which emerge through the cone openings, disperse, and repeat the process. The third generation of aphids consists of both males and females which mate and lay their eggs on Witch-hazel. The aphids that hatch from these eggs create the conical galls found on Witch-hazel leaves.
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Witch Hazel Flowering
Witch Hazel (Hamamelis virginiana) is nature’s final fanfare of the fall. As colorful fall foliage begins to disappear, the yellow strap-like petals of Witch Hazel’s fragrant flowers brighten denuded woods. This year, with a somewhat late peak foliage, they are both providing brilliant colors to the landscape at the same time.
Witch Hazel flowers are pollinated by moths that are still active this late in the season, and develop into small, hard capsules that remain dormant throughout the winter. During the following summer, these capsules develop to the point where they expel two shiny black seeds 10 to 20 feet away from the tree. The seeds take another year to germinate, making the length of time from flowering to germination approximately two years.
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More Buds
The previous “bud scale” post engaged readers to an extent that made me feel another post with additional buds to scrutinize would be welcome. Apologies to non-woody plant aficionados!
When identifying woody plants in winter, one takes advantage of everything a tree or shrub has to tell you: bud/branch arrangement (opposite/alternate), bark, silhouette and terminal buds. Buds are so revealing that they alone can immediately tell you what species you are seeking to identify. Is there one bud at the tip of each branch (willows) or multiple terminal buds (red oak)? Are there bud scales (no-witch hazel; yes- bigtooth aspen)? If so, what are their number (willows – one) and arrangement (overlapping, like shingles – red oak)? Are the buds red (striped maple), brown (witch hazel), yellow (bitternut hickory), green, or some combination of these colors? Are they pointed (bigtooth aspen) or rounded (willow)? Every species of tree has buds with a unique combination of these characteristics. Now is the time to observe them, as some will soon start to open.
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