Broom standing up on its own 201612/9/2023 ![]() This was collected by me and propagated by Bruce, before the parent tree and broom were destroyed by a DOT work crew doing “roadside maintenance”. My first collected hemlock broom, that I named ‘Nantahala’, had a truly spectacular presentation and was conveniently accessible from the ground, so no climbing was required. Here are some examples of hemlock witch’s brooms that I have collected and propagated over the last decade. And while I now have a small propagation chamber of my own, I continue to share collected broom specimens and work with Bruce whenever possible. For the latter I was able to draw on the knowledge and experience and facilities of landscape conifer specialist Bruce Appeldoorn as my propagation mentor (). For this, you may need a climber to get up the tree to the broom location and a horticulturally oriented person who has a propagation misting setup that you can use. I would like to encourage others to “keep an eye out” for wild hemlock witch’s brooms and to find a local source for help in collection and propagation of these interesting growth forms. ![]() But you should always check the back of a broom to confirm that it is genetic in origin, as a broom will have a clear demarcation between the normal and altered growth at the point of the genetic mutation. In the example below, all three kinds of differences appear to be present. First, you will note some obvious differences in either growth form, or needles or color that makes the broom stand out from its parent tree and surroundings. My best guess is that there are brooms everywhere, but those along roadways are easier to spot.īelow is an example of what you will observe with a hemlock witch’s broom. ![]() There are some theories that this tendency for conifer witch’s brooms to be found-along-roadsides is due to some causal role of sunlight or other radiation in the creation of the bud mutations. And the majority of these discoveries have been along public roadways passing through hemlock areas. Most of my hemlock broom “finds” were first spotted by a local friend, Nelson, who has become a “conifer broom scout” by avocation. But even a highly HWA-resistant broom cannot survive the death of its less resistant parent tree, which makes the collection and propagation process important for both scientific and horticultural purposes. This genetically-based HWA resistance is also relevant to researchers working on strategies to enhance HWA resistance in our native Eastern hemlocks. And one of the only positive effects of the heavy HWA “biological avalanche” that swept into the Southern Appalachians has been to increase the visibility of hemlock witch’s brooms (at least for brooms that have higher HWA resistance than the parent tree). One of the benefits of being out-and-about in hemlock-rich areas is the occasional discovery of witch’s brooms on wild hemlocks. ![]() See Swartley’s (1984) The Cultivated Hemlock for more information on the many hemlock cultivars. As a result, there are hundreds of named hemlock cultivars, most deriving from the Eastern hemlock ( Tsuga canadensis). But it can also be done indirectly, by utilizing seedlings produced by such genetically altered brooms. Sometimes this is done directly – by collecting and propagating plant materials from brooms. Horticulturalists have been utilizing such genetic variations, involving differences in conifer growth form or foliage or color, for centuries. And these genetic variations, which can occur on all native conifer species, can be captured by propagating the genetically altered “mutant growth”. In contrast, many witch’s brooms found on conifers originate from genetic “bud mutations”. And such acquired witch’s brooms do not have a genetic basis. In most cases, these abnormal growths on deciduous trees and shrubs are due to damage from bacteria, fungi, insects or some other physical injury to the plant. The term “witch’s broom” refers to a growth on a plant that is not “normal” for its host plant.
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