Evergreen Shrubs for Relatively Wet Areas
Published 5:30 am Saturday, January 21, 2023
Plants in Louisiana experience a lot of rainfall just about every year and need to be able to tolerate a good deal of soil moisture to survive here. This is especially so in low areas and on sites with a water table (where soil stays saturated for an extended period) close to the surface.
This week, I’ll address the topic of evergreen shrubs for such sites. All plants discussed here are native to the southeastern US, and most have irregular forms better suited to naturalistic landscapes than sites where a formal look is desired.
Wax myrtles (Myrica cerifera AKA Morella cerifera), also called bayberries, are native to the southeastern US. I consider them evergreen, though I’ve also seen them described as “tardily deciduous,” meaning that they lose their leaves late. I recently planted one near a baldcypress, where I want some greenery in the winter.
Leaves of wax myrtle are fragrant, and wax from fruit is used to make bayberry candles. Native forms of wax myrtle vary in size, reaching 20 feet tall and wide, or larger. Dwarf varieties are available. Plants produce multiple trunks.
Wax myrtles can be hedged if someone prefers a more manicured appearance. While they tolerate moist areas, they also perform well on drier sites. They grow in full to partial shade or dappled sun.
I find it interesting that wax myrtles “fix” nitrogen. In other words, they have microbes (fungi, in this case) associated with their roots that take nitrogen from the air and make it available to the plant, thereby fertilizing it. While many plants that fix nitrogen are in the legume (bean) family, wax myrtle is not.
Titi (Cyrilla racemiflora) looks somewhat like wax myrtle and also grows on moist sites in full sun to partial shade. It loses its leaves in the winter in the northern part of its native range but is semi-evergreen to evergreen in the Deep South. Titi produces elongated white flowers in late spring.
Dahoon holly (Ilex cassine) can grow to approximately 25 feet tall and 8 feet wide but is often smaller. As with other hollies, female and male flowers occur on separate plants. Female-flowered plants produce red berries.
The native form of yaupon holly (Ilex vomitoria) can also grow to about 25 feet tall. However, there are dwarf cultivars often used as foundation plants, filling a similar niche as boxwoods or Japanese hollies like ‘Helleri’ and ‘Compacta’. If you want a large yaupon that’s different than the norm, there are weeping and yellow-fruited forms. Yaupon leaves are smaller than those of dahoon holly. Like wax myrtle, yaupon hollies grow well on dry sites, too.
An interesting aspect of yaupon is that the leaves contain caffeine and have been used to make tea. The scientific name refers to its historic use as an emetic and suggests what happens when an excessive amount of the tea is consumed.
If you have an area that is both moist and shady, you might consider the Florida anise (Illicium floridanum). This shrub grows to approximately 10 feet tall and 8 feet wide and produces attractive maroon flowers in spring. The smell of the flowers has been described as like that of a fish market, so take this into consideration when you decide where, or whether, to plant it.
Let me know if you have questions.
Dr. Mary Helen Ferguson is an Extension Agent with the LSU AgCenter, with horticulture responsibilities in Washington and Tangipahoa Parishes. Contact Mary Helen at email@example.com or 985-277-1850 (Hammond) or 985-839-7855 (Franklinton).