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Gardening Answers Knowledgebase

Plant Answer Line Question

Keywords: Color, Parrotia

I have a Parrotia persica tree that has never developed the dramatic purple color that the Sunset Western Garden Book says it should have. Its leaves do turn gold in the fall. What nutrient is it missing? It gets full sun, and is at the top of a sloping area of lawn. I have wondered if the run-off could be leaching something from the soil.

Any suggestions?


According to this article in Fine Gardening online, Parrotia persica only has that purple color as the leaves emerge in spring:
"Reddish-purple when unfolding in spring, the leaves are a lustrous dark green in summer, and yellow to orange or scarlet in fall. Leaves hold their color for a long period. Older branches and trunks develop an exfoliating gray, green, white, and brown color that is a welcome asset in the winter garden. It grows successfully in Zones 4 to 8, tolerates sun and partial shade, and is easy to transplant. Often, vegetatively propagated forms offer more reliable fall color."

According to Dirr's Hardy Trees and Shrubs (Timber Press, 1997), there is some variability in the foliage color: "[...]the developing leaves are reddish-purple to bronze, maturing to lustrous dark green." I don't believe missing nutrients are the reason you are not seeing dramatic purple color but if you are concerned, you can do a soil test for any imbalances.

Date 2018-03-14
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Plant Answer Line Question

Keywords: Color, Conifers

What makes the blue color on some conifers?


I am by no means an expert on plant physiology, but I believe it is the waxy coating (cuticle) on the needles that makes them look blue, as confirmed in this article about a variety of Colorado blue spruce by Edward Gilman and Dennis Watson on the website of University of Florida Extension:

"[....] the wax coating on the needles of Blue Spruce which give the blue color can be washed off by some pesticides."

Here is similar information from Montana State University Extension (page 14):
Excerpt re: Colorado blue spruce:
"The bluish color of the leaves of some of the trees results from a wax (cutin) accumulation, which is genetically controlled. This doesn't satisfactorily explain why blue conifer needles would be any different from those of green conifers (whose needles are also waxy), though."

The following article by John Clark and Geoffrey Lister in Plant Physiology, vol. 55, 1975 has a complex technical explanation:
"The observed differences in relative pigment complements can, therefore, partially account for the differences between the action spectrum for red alder and those of the conifers as a whole. In particular, the increasing carotenoid-Chl ratios determined for red alder (0.38) and the two green conifers, Douglas fir (0.54) and Sitka spruce (0.67) would seem to be the factor responsible for the differences between their action spectra. The same explanation, however, cannot alone account for the range of differences seen in the action spectra for the four conifers. No evidence was found to support differential degrees of screening by an extrachloroplast blue-absorbing pigment reportedly present in some conifer needles (2). One is therefore led to believe that an additional factor must be responsible for the differences between the green and 'blue' spruces. Differences in apparent leaf coloration, arising from changes in relative spectral reflectance attributable to varying leaf cuticle structure, seems to be the most plausible explanation."

Date 2018-06-27
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May 31 2018 13:14:08