Sea Oats, River Oats

 

Uniola paniculata, Sea Oats grow on the dunes
of the Southeastern United States.
Huntington Beach State Park, South Carolina. 

Sea Oats (Uniola paniculata) are spectacular plants of beach dunes in the Southeast.  These grasses can grow to six feet in height and thrive is harsh conditions of sunlight, heat, salt and drought.  The only source of fresh water for Sea Oats is rain and because of the sandy soil of their dune habitat that water drains quickly.  Sea Oats will not wilt until soil moisture reaches about 1% but recover quickly when water returns.  Too much water is harmful to Sea Oats.  If roots are waterlogged, even for a few days will cause the plant to die.  Sea Oats have extensive root systems and they are important plants in stabilizing dunes. The flowers of Sea Oats are born in flat structures called spikelets.  The spikelets give the plant their name because they resemble those made by oats.  Fruits mature in the spikelets and the seeds are carried away on the wind.  Marsh Rabbits (Sylvilagus palustris) that inhabit the dunes eat the fruits. Sea Oats are also a major food source for the Perdido Key Beach Mouse (Peromyscus polionotus trissyllepsis).  This federally endangered rodent is found only on Perdido Key in the panhandle of Florida where Sea Oats are abundant.  Sparrows and Red-winged Blackbirds (Agelaius phoeniecus) are also major consumers of Sea Oats.  

Sea Oats plant with mature fruits.
Palm Beach County, Florida.

Sea Oat fruits.
Palm Beach County, Florida.

River Oats (Chasmanthium latifolium) resemble Sea Oats.  River Oats are grasses that reach 3-4 feet and make oat-like spikelets bearing flowers.  As their name suggests, River Oats grow along river banks often in the riparian forest understory.  River Oats are very shade tolerant and are popular for landscaping shady areas.  River Oats are found from New York to Florida, from the Midwest to Texas and south into Mexico.   River Oats were once classified in the same genus as Sea Oats and the resemblance is striking, but are now recognized as distinct genus.  Many animals including; White-tailed Deer (Odocoileus virginianus), Northern Bobwhite (Colinus virginianus) and the larvae of several moths and butterflies consume River Oat fruits and leaves.   

River Oats (Chasmanthium latifolium) growing beside a creek.
Rowan County, North Carolina.

River Oat flowers.
Rowan County, North Carolina. 

Sea oats stand as sentinels on the dunes, protecting the shoreline.  They are often planted during beach restoration and are protected by law in many southeastern states.   While Sea Oats are on the front line of erosion control, River Oats grow in creek-side forests, their seed heads nodding as they watch the river flow.

River Oats.
Rowan County, North Carolina.