11-21-2017, 01:59 PM
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#1
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A Bee's Best Friend
Join Date: Mar 2009
Location: Chicago Illinois USA
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Cultivar conundrum, Xerces Society
Something to think about.
https://xerces.org/2017/11/21/pickin...var-conundrum/
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Some cultivars, bred for foliage color, may even be toxic to insects. One study compared cultivars of ninebark (Physocarpus spp.), which has been bred into dozens of cultivars featuring various shades of red or gold foliage. In the study, ninebark beetles (Calligrapha spiraeae) were fed leaves of the cultivars ‘Monlo’ (deep red foliage) and ‘Dart’s Gold’ (chartreuse colored leaves) vs. the straight species. The beetles showed a strong preference for the regular green foliage and the foliage of the yellow cultivar, and avoided ‘Monlo’. Observers speculate that, because dark red foliage is typically high in anthocyanins, a compound which may be poisonous to herbivores, the beetles avoided the plant. It can be reasonably inferred that the caterpillars and moths that host on ninebark are also avoiding these cultivars, which are widely sold as native and beneficial to pollinators.
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Knowing the history of the cultivar, ‘Goldsturm’ is a fairly pure cultivar that hasn’t been tinkered with too much, but has merely been selected for its compact nature and propensity to flower more heavily than the straight species. For this reason, we can assume it retains many of the same properties that attract pollinators who may use it as a host plant or nectar source – but without studying it against the non-cultivar, we can’t say for sure.
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Cindy Haynes of the Dept. of Horticulture at Iowa State explains the difference:
“Varieties often occur in nature and most varieties are true to type. That means the seedlings grown from a variety will also have the same unique characteristic of the parent plant. For example, there is a white flowering redbud that was found in nature. Its scientific name is Cercis canadensis var. alba (the varietal term “alba” means white). If you were to germinate seed from this variety, most, if not all seedlings would produce white flowers.
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“Cultivars are not necessarily true to type. In fact, cultivar means “cultivated variety.” Therefore, a cultivar was selected and cultivated by humans. Some cultivars originate as mutations of plants; other cultivars could be hybrids of two different varieties. To propagate true-to-type clones, many cultivars must be propagated vegetatively through cuttings, grafting, and even tissue culture. Propagation by seed usually produces something different than the parent plant.”
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