Beautiful gardens by William Johnson
Q: I have the same ugly blob in my mulched flower beds at home that is growing on the surface of the mulch in the vegetable bed in the picture left. What is it and is it harmful?
A: I address some gardening questions by e-mail, some by phone and some on-site. This question was asked by a gardener attending this month’s home fruit growers tour. The inquiring gardener was amazed – and a bit relieved – to come across blobs in the mulched vegetable beds at one of the tour sites. They looked just like the blobs growing on top of the layer of mulch in her flowers beds back home.
The growth is produced by organisms known as slime molds. The brightly colored blobs usually spread across mulched beds when weather conditions are favorable – high rainfall, high humidity and raised temperatures. Needless to say, the weather conditions over the past few weeks have provided an ideal growing environment to stimulate their growth.
Fuligo septica is the species of slime mold most common in our area; this species is typically brightly colored – ranging from yellow and pink to red, depending on the stage of growth. Its growths can expand to the size of a medium-size pizza before hardening. As they begin to dry out, the bright colors fade to brown and tan. Breaking up the dried blob will reveal a dark brown to black inner core that contains the mold’s spores.
In their early stage of development on mulch, slime molds produce structures that look eerily like a creature in the starring role of a science-fiction movie about blobs.
Slime molds do not present a danger to humans or pets. They help break down plant matter, which aids the microorganisms essential to recycling plant nutrients and supporting healthy plant growth. Like several other critters that creep homeowners out, slime molds are actually good for the garden.
Q: What’s the difference between a tree and a shrub?
A: This is an interesting question that would seem to have a one-size-fits-all answer. If we look at only the most obvious examples, there would be no debate over the difference between trees and shrubs.
Nobody would look at mature oak trees and call them “shrubs”. Nor would anyone mistake Indian hawthorn shrubs for trees. But we’re dealing with Mother Nature here and the distinction is not always clear-cut.
We are challenged when we try to categorize everything under neat black-and-white headings that make humans feel most comfortable.
The generally acknowledged definition of a tree is a “woody plant having one erect trunk at least three inches in diameter at a point four feet six inches above the ground, a definitely formed canopy or crown of foliage and a mature height of at least 13 feet”.
In contrast, a shrub is characterized as a “woody plant with several perennial stems that might be erect or lie close to the ground, usually with a height less than 13 feet and stems no more than about three inches in diameter”.
The above descriptions provide sufficient distinctions to categorize most trees and shrubs. As is true with most things in life, there are exceptions. Some trees might have several trunks – crape myrtles being a prime example.
Some shrubs can be shaped into a small tree by training one trunk. One of my master-gardener volunteers has shaped his Texas red tip photinia to grow as a small tree with a height of 16 feet and a trunk diameter of five inches.
And where do banana trees fit? While we call them banana trees, they do not produce any woody growth. They are among the world’s largest plants without woody stems.
The banana is closely related to ginger and ornamental plants such as birds of paradise, amaranths and canna lilies. The banana is not a tree but the world’s largest perennial herb.
William Johnson is a horticulturist with the Galveston County office of Texas A&M AgriLife Extension Service. Visit his website at aggie-horticulture.tamu.edu/galveston/index.htm.
Editor’s note: This article first appeared in The Post on May 25 last year.