Cloverleaf

 

Crimson Clover (Trifolium incarnatum) in a mountain meadow.  
Ashe County, North Carolina. 

Clovers (Trifolium sp.) are small herbaceous plants with a large impact; agriculturally, ecologically and culturally.  Trifolium is a member of family Fabaceae which includes peas, beans, vetches and acacias.  Clovers are usually low growing annuals and are native to all continents except Australia and Antarctica.  A defining characteristic of clovers is their three-part, compound leaves that give the genus its name. 

The leaves of clover play a major role in myth and legend.  Patrick, the patron saint of Ireland, is reputed to have used the three leaflets of clover to explain the Trinity to the pagan Irish he came to convert to Christianity.  However, clovers never appeared in St. Patrick’s writings so this story is probably apocryphal.  The ancient Irish word for clover was corrupted in English to give us shamrock. The association of shamrock/clover with St. Patrick led to its adoption as a symbol of Ireland.

I found a four-leaf and three leaf White Clover (Trifolium repens) in the same patch.  
Rowan County, North Carolina. 

Another interesting tradition is that four-leaf clovers are lucky.  Normally a clover has three leaflets but rarely a plant will make a leaf with four.   Since four-leaf clovers are rare, about 1 in 5000, finding one is considered good luck.  I think finding a four-leaf clover has more to do with persistence than luck.  

Roots of White Clover with root nodules containing
nitrogen fixing bacteria.
Rowan County, North Carolina. 

Clovers make small flowers grouped in compact heads.  They flower from early spring to late summer and are important nectar sources for a variety of bees.  Clover honey has a mild taste and is much in demand.  Clover plants have a high protein content.  Farmers grow it for silage and as a ground cover in crop rotation.  The large amount of protein in clover is a result of nitrogen fixing bacteria (Rhizobium sp) in the roots.  The bacteria invade the roots and induce the plant to make nodules where the Rhizobium converts nitrogen gas to amino acids.  The clover transfers organic nutrients to the bacteria in the nodule and the bacteria in turn provides amnio acids to the plant. Clover and its bacteria can add hundreds of pounds of nitrogen to an acre of soil during a season as a cover crop. 

Flowers of White Clover.
Ashe County, North Carolina.

Many of the species of Trifolium in the Southeast United States are native to Eurasia that have been become naturalized and now grow wild. Perhaps the most common clover in our area is White Clover (Trifolium repens).  This import from Europe is also called Dutch Clover and, of course, has white flowers.  The leaflets of this species often sport white, V-shaped marks.  

Red Clover (Trifolium pratense) in flower. 
Ashe County, North Carolina.

The flowers of Trifolium pratense, Red Clover, are not really red but rather a delicate pink.  Like White Clover, Red Clover leaflets can have V-shaped markings.  

Low Hop Clover (Trifolium dubium). 
Davidson County, North Carolina. 

Low Hop Clover, Trifolium dubium, is a low-growing clover with small yellow flowers.  This plant gets its name from the flowers that occur in heads that resemble the fruits of Hops (Humulus lupulus), an essential ingredient in beer. 

Rabbit Foot Clover (Trifolium arvense).
Rowan County, North Carolina. 

Rabbit Foot Clover (Trifolium arvense) has dense heads of rose-colored flowers.  The flowers have sepals that are tipped with long white hairs that give the plant a furry appearance and its name, Rabbit Foot.  Trifolium arvense thrives in dry, sandy soil, along roadsides and in what botanists call waste places.  

Crimson Clover.
Ashe County, North Carolina.  

Trifolium incarnatum, Crimson Clover, has the most stunning flowers of all the clovers in the Southeast.  They are bright crimson and are often found growing in large patches along highways and in meadows.   

A field of Crimson Clover.
Ashe County, North Carolina. 

All the clovers discussed so far were imported to North America, mostly to serve as cover crops or livestock feed.  There are two native clovers in North Carolina, both of which have limited ranges and small population sizes.  Carolina Clover (Trifolium carolinianum) is native to the Coastal Plain and is significantly rare.   Buffalo Clover (Trifolium stoloniferum) is an endangered species.  As its name suggests, Buffalo Clover was associated with eastern prairies and savannahs that were maintained by American Bison (Bison bison) herds. With the loss of these large herbivores in the east, the habitat for Buffalo Clover has diminished and it is now found in only a few locations.

Red Clover. 
Rowan County, North Carolina. 

Clovers come in a satisfying range of colors, shapes and sizes.  A meadow with clovers and abuzz with bees is a treat in springtime.  These humble plants fix nitrogen that reduces the need for fertilizer for crops.  Although most of the clovers we see in our area are introduced species, I am a fan.