Q. I am hopeful that you can help me in identifying what this “growth” is. It is sitting atop a Pride of Madeira plant along a pathway in our city park. It is velvety to the touch.

A. What a nice mutation of Pride of Madeira you found. This type of mutation is commonly referred to as fasciation. It can be caused by damage to the plant by any one of an assortment of factors such as virus, bacterium, frost, chemical or mechanical injury, or even spontaneous genetic mutation. When the damaged plant tries to grow new shoots or stems, they become fused together and the fasciation occurs. It is not typically contagious, and affected plants may even “outgrow” the mutated growth.

Sometimes the mutation is considered attractive by the horticulture industry and is preserved and propagated. The cultivated forms usually have cristata or monstrosa tacked onto their botanical name to distinguish it from the non-mutated form. Pictured is a fascinated form of Euphorbia lactea with a fan-like growth habit that I’ve had for many years. The normal non-fasciated growth is slender and vertical but this one is fasciated and so it’s called Euphorbia lactea “cristata.” Sometimes it tries to put out a non-fasciated stem and I just cut it off to preserve its ruffled form.

Another, more common garden plant with fascinated growth is the cockscomb celosia, Celosia cristata, which can be relied upon to produce colorful fascinated flower heads that somewhat resemble velvety brains. In this case the mutation is stable. So, I hope that I have satisfied your curiosity. Congratulations on your interesting discovery.

Q. Last week we were shopping for a peach tree but were confused by some of the labels. What is the difference between fruit trees labeled “dwarf”, “semi-dwarf”, and “genetic dwarf”?

A. A tree labeled “dwarf” or “semi-dwarf” is a standard variety grafted onto a dwarfing rootstock. Many different dwarfing rootstocks are used, and they reduce the ultimate size of the tree anywhere from 30 to 70 percent. Generally, a tree labeled as dwarf will attain a height up to half that of a standard variety, and a semi-dwarf will reach a height of 50 to 70 percent of the standard variety. A “genetic dwarf” is a naturally occurring dwarf cultivar and they are typically grafted to a standard rootstock. These trees remain quite small (6-10 feet tall) and are suitable for growing either in the garden or in containers. All will produce full-sized fruit, regardless of tree size.

Ottillia “Toots” Bier has been a UC Cooperative Extension master gardener since 1980. Send comments and questions to features@pe.com.

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