Plant of the Month

Garden Workhorses!


Sedges, botanically known as Carex are truly an underused group of grass-like plants for the Garden.  For years, the more flashy evergreen species from Asia and New Zealand have stolen the limelight among gardeners.   Of late, I have become more enamored with our native sedges, many of which can serve as gardenPOM workhorses in a variety of less than ideal conditions.  
Carex is a member of the family Cyperaceae; with over 2,000 species, it is one of the largest plant families.  Sedges are known for their ‘edges’ or the serrated leaf margins. The name Carex was coined by Carl Linnaeus (1707-1778) and comes from the Greek Keiren, which means to cut – a reference to the leaves.  Interestingly, for those who enjoy words, the name Sedge was derived from the Old English Sagu, which means saw, again a reference to the toothed leaf margins!  The flowers of sedges are typically not very showy,but do possess a subtle beauty for the inquisitive gardener.  Unlike grasses, the flowers or inflorescences of Sedges are monoecious, with the male and female organs found on separate ‘flowers’ of the same plant.  In fact, the separate flowers are often on the same stem, with the male flowers located just above the female counterparts.
Carex pennsylvanica or Pennsylvania Sedge was one of the first native species whose assets were broadly promoted to the gardening community.  The species epithet was created by Jean Baptiste Lamarck (1744-1829) for the general area from which it was collected.  It is also called Oak Grass, since it is often found growing amongst Oak Forests.  This species has very attractive and delicate foliage that is a mere ⅛” wide and grows up to 12” in length.  The plants are rhizomatous, meaning that they spread by undePOMrground stems, which also allows it to quickly spread and become a dense groundcover.  As the foliage grows, it refuses to stand upright, but prefers to lie down against its neighbor, producing an overall effect similar to rushing water (as seen above).  As a result, even though the foliage is 12” long, the overall height only reaches 6-8”.  This plant thrives in dry shade, making it a great alternative to turf grass, Pachysandra, Vinca and English Ivy.  In addition, it can be mowed should the gardener wish and it tolerates light foot traffic!  With the advent of December’s cold, the foliage fades to tan and remains attractive through the winter months.  Come spring, the new foliage literally emerges up and through that of the previous year (as seen in the photo, above right), making the plant not only very low in maintenance, but self-mulching!

Carex cherokeensis has been growing at Rutgers Gardens for the past 3 years, but it was not until the last winter that I realized it remains green through the first half of winter in NJ!  The picture at left was taken in January.  Named in 1824 by the German-American botanist and mycologist Lewis David von Schweintz (1789-POM1834), the plant was named after the town of Cherokee Texas.  Native from Missouri and North Carolina south to Texas and Florida, Cherokee Sedge is very heat and drought tolerant.  Unlike it afore mentioned cousin, the 12” long foliage not only remains upright and arching, it is also glossy! The plant produces shorter rhizomes than Oak Sedge, but it still knits together with ease and makes a very effective groundcover.  Plants prefer shade to part shade, but they do adapt well to full sun and will grow well in dry to very moist soils, making it ideal for rain gardens!  In NJ, the plants bloom from mid-May through July, with the flower stems stretching to 18” and turning to an attractive straw color when the seed is mature.
Carex leavenworthii is yet another tough groundcover for the dry woodland garden.  The species was named in 1846 by Chester Dewey (1784-1867), who was an ardent fan of Carex and ultimately described 97 species and varieties of this genus.  In fact, the study of the genus Carex is called caricology.  The species epithet honors Dr. Melines Conklin Leavenworth (1796-1862), who served as an assistant surgeon in the army and was also a plant collector!  Unlike the above two species, Leavenworth Sedge is clump forming, with ⅛” wide and 12” long fine and delicate foliage.  The foliage is dark green in shady areas, become more olive green with increasing exposure to sunlight.  It fills in large areas through the production of seeds.  Like Oak Sedge, it can be cut several times throughout the season for a more turf-like appearance, which also removes the flower and seed heads, eliminating any potential to seed about and potentially become weedy.
All these sedges, plus Carex albicans, the White Tinged Sedge with its small yet attractive off-white inflorescences (as seen below on the right) have been planted out in mass at Rutgers Gardens by the Rain Garden.  The intent is to both evaluate their garden potential and to showcase them to interested gardeners.  The Gardens will be showcasing many other native sedges that are excellent candidates for the Garden in the years to come.  They are great for creating a nice groundcover fabric through which other perennials and woody plants can emerge.  With little need for additional water and fertilizer and undesired by deer, these workhorses for the Garden will only increase in popularity as awareness grows.  Spread the word!POM