Question and Answer - Indiana Yard and Garden - Purdue Consumer Horticulture

Question and Answer

Q.  Can you please tell me the name of the flower that is in bloom in this photo? The flowers came back in bloom for around three years and died out. It grows around 4-5 feet tall. The stems are a reddish color. It starts blooming in June and blooms until frost. My brother gave me this flower. And there was no name on the pot. It is a beautiful flower. I hope you can help me.

A. This lovely flower looks like one of the so-called Hardy or Mexican petunias, Ruellia brittoniana. The plant is a tender perennial, even in Florida, so you must have quite a protected location to have been able to get it to overwinter for even a couple of years. There are a number of cultivars of this species. ‘Purple Showers,’ ‘Colobe Pink’ or ‘ChiChi’ would appear to be a reasonably close match; it is difficult to tell color in your picture. While you are unlikely to find many local sources for this plant, you can do a bit of Internet searching for Ruellia brittoniana to find several tropical plant suppliers. Here’s a couple of suggested retailers online, but no discrimination or endorsement is intended: (Ohio) and Carolina).

Q. We acquired a start of a plant from my husband’s elderly aunt in Kentucky, but have never known what it is. It dies during winter but comes up again in the spring. It’s very fast growing. The stalks are hollow like bamboo, and roots travel underground to make new plants. It has white whispery “flowers” in the summer, which deepen to a mauve color in the early fall and remain until winter. If I keep the shoots cleared, it will develop into a 5-6-foot bush by early summer and be about 5 feet round. Can you tell me what this is? Thank you.

A. This vigorous perennial is known by quite a few aliases, perhaps in an attempt to rid itself of its terribly invasive reputation! Botanically, this plant can be listed as Fallopia japonica, Polygonum cuspidatumP. japonica, or Reynoutria japonica. More commonly, it is known as Mexican bamboo or Japanese knotweed. There are some dwarf cultivars as well as a few that form clumps rather than running wildly through the garden. There are also selections with variegated foliage.

You can see photos and a bit more info about the invasive forms of this plant at

Q. I have a maple tree that is doing poorly. Last year some of the leaves withered and died before fall. The limbs that those leaves were on turned a yellow/green color. This spring, those same limbs are yellow/green and not producing leaves. I did notice some bark is split on the trunk. Could there be insects under the bark? And, if there is, what can I do to try to save my tree? I also noticed some green moldy looking spots. Could it be some kind of fungus? Thank you in advance for your advice.

A, It’s difficult to say what the cause might have been, but it does sound like at least a portion of the tree has died back. A split in the bark is not necessarily a fatal injury, but frequently results in some branch dieback on top. The question is, what caused the split in the bark? Young, thin-barked trees are susceptible to what is known as frost cracking or sunscald injury, most frequently occurring during late winter on a warm, sunny day. The sun warms the bark and the underlying wood, which causes the tissue to expand. But when the sun goes down, the temperature drops abruptly, such that the bark contracts faster than the wood, resulting in a bark split. Maple, tuliptree, crabapples, and many fruit trees are susceptible to this injury in their first few years of growth. There’s not much that can be done about the split after the fact, but it can be prevented by applying tree wrap in late fall and removing the wrap in early spring.

I suspect the green “moldy” spots on the bark are lichens, harmless symbiotic organisms composed of a combination of fungi and either algae or cyanobacteria. Together, they live as one organism and are only using the bark of your tree for anchorage; lichens are not parasites. More information on lichens can be found at

Any of the limbs that did not leaf out this year should be pruned out all the way back to healthy tissue, either above a side branch that is growing in the direction you want future growth, or perhaps back to the main trunk, depending on the extent of dieback. If the dieback continues, you might want to contact the Purdue Extension office in you county and/or the Purdue Plant & Pest Diagnostic Lab to submit samples (digital image or live branch) for diagnosis. See for more sample submission instructions.

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