Vascular Plants of North Carolina
Account for Coastal-plain Yellow-eyed-grass - Xyris ambigua   Beyrich ex Kunth
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Section 5 » Order Commelinales » Family Xyridaceae
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AuthorBeyrich ex Kunth
DistributionCoastal Plain and Sandhills; Catawba and Rowan counties in the Piedmont. Rare on the Outer Banks (Jockey's Ridge State Park). A specimen from Macon County is a student collection from a classroom exercise and not collected locally.

Coastal Plain, southeastern VA to southern FL and eastern TX; scattered records inland, such as central TN.
AbundanceFrequent to common in proper habitats in most of the Coastal Plain, though scarce in the far eastern counties. Very rare and local into the Piedmont.
HabitatWet, sandy or peaty, acidic soils of Longleaf Pine-Wirgrass savannas and flatwoods, blackwater streamheads and ecotones, pitcher-plant seeps and bogs, margins of beaver ponds and impoundments, depressions and sinkhole ponds, interdune seepages.
PhenologyFlowering and fruiting May-September.
IdentificationThis is one of our larger yellow-eyed-grasses at 1.5-3 feet tall. The leaves are rather broad (up to 1/2-inch) and pale pink or straw color at the base. Flowers open in the morning. The keel (outer margin) of the lateral sepals bears many short prickles. Tall Yellow-eyed-grass (X. platylepis) is very similar in size and gestalt, but has obviously twisted leaves, deep pink to red bases of the leaves, lateral sepals irregularly cut, and flowers opening at midday or later.
Taxonomic CommentsMembers of Xyris are easy to identify to genus, but can be a challenge to identify species. Careful observation of a few features with a hand-lens is usually sufficient. Close attention must be paid to the flowering head, which is composed of overlapping brown scales. Immediately behind each scale are two brown "lateral sepals"; the margins of these may be feathery or irregularly lacerate (cut into narrow segments) or finely cut into short, comb-like prickles. Lateral sepals may be hidden or a bit longer than each scale. The flowers themselves are usually of little diagnostic value, other than time of flowering -- morning vs. afternoon. Seed size and ornamentation can also be useful characters, but require a dissecting scope to see well. Note also whether leaves and scapes (stems) are twisted and the color of the basal portion. All species have 2-ranked leaves, but in some species the leaves are arranged in a broad, fan-like shape. Finally, note the leaf and stem surface texture -- whether smooth of with little pale bumps. See Godfrey & Wooten (1979) for detailed descriptions and drawings.
Other Common Name(s)Savanna Yellow-eyed-grass (the preferred name, however, for X. flabelliformis)
State RankS4
Global RankG5
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