Grasses and Sedges of the Oak Savanna

A restored savanna generally has an extensive groundlayer of grasses. In fact, some older definitions of savanna required prairie grasses as a major part of the groundlayer. However, because of the high heterogeneity of the savanna environment, presence of prairie grasses will depend considerably on available light, which will be influenced by how open the forest canopy is. A savanna with widely spaced open-grown oaks (perhaps 10% cover) can be considered a prairie with occasional scattered trees. More closed canopies, even those with large open-grown oaks, may have prairie grasses only on the edges.

Grasses can be divided into two classes depending on whether they grow best in the cooler or warmer part of the growing season. These are called "cool season" and "warm season" grasses. They differ in how they handle the photosynthesis process during hot periods. The cool season grasses essentially "shut down" during the summer heat, whereas the warm season grasses are able to store carbon dioxide during hot days and then utilize it for photosynthesis during the cooler night periods.

In the Midwest the principal prairie grasses are the warm season grasses listed in the table below. On the other hand, the cool season grasses shown in the table begin growth early and are often finished flowering and beginning to set seed just when the warm season grasses are beginning to thrive. Most of the cool season grasses can best be called "savanna" grasses.

In "open" savannas, those that are more prairie in character, the warm season grasses may predominate. In more closed savannas, the cool season (savanna) grasses thrive. These cool season grasses begin growing early in the season. In addition to growing in savannas, they are often also present in more mesic habitats, sometimes even wet mesic, and may even be found in nonsavanna habitats such as lowland (riparian) forests.

Warm and Cool Season Grasses
Latin name Common name Warm or cool season
Andropogon gerardii Big bluestem Warm
Bouteloua curtipendula Side oats grama Warm
Bromus kalmii Kalm's brome Cool
Bromus latiglumis Ear-leaved brome Cool
Bromus pubescens Woodland brome Cool
Calamagrostis canadensis Blue joint grass Cool
Elymus canadensis Canada wild rye Cool
Elymus riparius Riverbank rye Cool
Elymus villosus Silky rye Cool
Elymus virginicus Virginia wild rye Cool
Koeleria macrantha June grass Cool
Panicum virgatum Switchgrass Warm
Schizachyrium scoparium Lttle bluestem Warm
Sorghastrum nutans Indian grass Warm
Spartina pectinata Prairie cordgrass Warm
Sporobolus heterolepis Prairie dropseed Warm
Stipa spartea Needle grass Cool

Warm season grasses
Big blue stem (Andropogon gerardii)
Little blue stem (Schizachyrium scoparium)
Side oats (Bouteloua curtipendula)

Cool season grasses
Virginia wild rye (Elymus virginicus)
Silky rye (Elymus villosus)
Riverbank rye (Elymus riparius)
Ear-leaved brome (woodland brome) Bromus latiglumis

Sedges of the savannas
Several species of sedges (genus Carex) are usually present in savannas. Most sedges have been less well studied, but one sedge, Pennsylvania sedge (Carex pensylvanica) is often the single most important herbaceous plant in an oak savanna. This sedge is clonal and forms large patches which prevent other herbaceous species from getting established.
Latin name Common name
Carex bebbii Bebb's sedge
Carex bicknellii Bicknell's sedge
Carex blanda Common wood sedge
Carex cephaloidea Clustered bracted sedge
Carex cephalophora Wood-bank sedge
Carex eburnea Bristle-leaf sedge
Carex gracillima Graceful sedge
Carex gravida Heavy sedge
Carex grayi Bur sedge
Carex haydenii Hayden's sedge
Carex hystericina Porcupine sedge
Carex lacustris Common lake sedge
Carex leptalea Bristle-stalked sedge
Carex meadii Mead's sedge
Carex molesta Field oval sedge
Carex muhlenbergii Muhlenberg's sedge
Carex normalis Greater straw sedge
Carex pauciflora Few-flowered bog sedge
Carex pensylvanica
Pennsylvania sedge
Carex pseudo-cyperus Cyperus-like sedge
Carex radiata Eastern star sedge
Carex rosea Stellate sedge
Carex rostrata Beaked sedge
Carex tenera Marsh straw sedge
Carex torreyi Torrey's sedge
Carex trichocarpa Hary-like fruit sedge
Carex trisperma Three-fruited sedge
Carex utriculata Common yellow lake sedge
Carex vulpinoidea Fox sedge
Cyperus esculentus Field nut sedge
Cyperus lupulinus Sand sedge
Cyperus odoratus Fragrant sedge
Cyperus squarrosus Bearded flat sedge
Eleocharis elliptica Elliptic spike-rush
Eleocharis olivacea var. olivacea Bright green spike-rush
Eleocharis ovata Oval spike-rush
Eleocharis tenuis Slender spike-rush
Eriophorum sp Cotton-grass
Juncus alpinoarticulatus Northern green rush
Juncus dudleyi Dudley's rush
Juncus effusus Common rush
Juncus gerardii Black-grass
Juncus greenii Green's rush
Juncus squarrosus Mosquito rush
Juncus tenuis Path rush
Schoenoplectus hallii Hall's bullrush
Schoenoplectus tabernaemontani Great bulrush
Scirpus atrovirens Black bulrush
Scirpus cyperinus Wool grass
Pennsylvania sedge, Carex pensylvanica

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