The year’s fourth month is the time for grasses to emerge and expand their respective territories. Some are native and well behaved, but others are not and will grow aggressively, if conditions meet their needs.
Torpedograss (Panicum repens) is a perennial grass with a creeping but forceful growth pattern and sharply pointed rhizomes. Stems are stiff and erect with folded or flat leaves and with an upper surface sparsely populated with short, hair-like projections.
The origins of torpedograss are uncertain, but it is not native to north Florida or the gulf coast. The common name comes from this plant’s ability to penetrate almost any obstacle.
The bloom is a loose cluster of branches, with each producing a flower about one-tenth an inch long. The seed heads are stiff and upright, but they frequently do not produce seeds.
Reproduction occurs primarily by rhizomes, but seeds will germinate in moist locations. These underground shoots can grow about half an inch daily, when growing conditions are ideal.
Cogongrass blooms are currently appearing on fencerows and roadsides in many panhandle Florida locations. This invasive species is very difficult to control and requires a persistent effort over multiple years to see removal.
These hardy roots will survive droughts and flooding. If damaged or broken, the root fragments remaining in the soil will produce a new plant and contribute to the dense, unseen, mat-like layer beneath the surface.
Much like torpedograss, cogongrass (Imperata cylindrica) is a warm-season, perennial grass species with an extensive rhizome root system. It is also dependent upon its roots as the primary tool for its expansion.
Its blooms are distinctive and commonly seen on disturbed sites such as fence rows. The long thin leaves and white flowing blooms easily sway in breezes, giving the location a tropical appearance.
It has been estimated at least 60% of the total plant biomass of this species is found below the soil surface. Unintentional relocation of the root material by mowing or earth moving equipment is a major cause for its spread.
Residential sites which have fill dirt or top soil brought in may be importing this exotic weed with highly invasive tendencies. Its roots quickly penetrate down to four feet in the subsoil as its leaves rise above the yard’s surface.
The off-center midrib on its long ribbon-like leaf makes identification of this invasive species simple. Unfortunately, control is much more difficult.
Burning offers no control once this weed is established, and herbicide application is complex and requires multiple applications.
Smutgrass is an invasive bunch grass, native to tropical Asia, and is a serious weed on roadsides and natural areas in Florida. There are two smutgrass species found in Florida.
Small smutgrass (Sporobolus indicus) and giant smutgrass (Sporobolus jacquemontii), which is also known as West Indian dropseed, are both perennials. The common name derives from a black mold growth which appears frequently on the inflorescence (bloom stalk) and upper leaves.
Seed production of both species occurs throughout the growing season, with new seed heads emerging shortly after mowing or burning. The most common in panhandle Florida, small smutgrass produces approximately 1,400 seeds per seed head and 45,000 seeds per plant annually.
The seeds, which are red to orange in color, remain on the seed heads after maturing and are spread by attaching to animals and machinery or by movement in water and on the wind. The seeds remain viable in the soil for at least two years.
In spring smutgrass blends easily with many other weeds and grasses. It may be hard to see, but the problem is still there.
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