(335)__Stuckenia filiformis var. occidentalis, commonly known as slender pondweed;

(336)__Suaeda calceoliformis, commonly known as American sea-blite;

(337)__Suaeda maritima ssp. richii, commonly known as Rich's sea-blite;

(338)__Subularia aquatica, commonly known as water awlwort;

(339)__Symphyotrichum anticostensis, commonly known as anticosti aster;

(340)__Symphyotrichum subulatum, commonly known as small salt-marsh aster;

(341)__Tanacetum bipinnatum, commonly known as Huron tansy;

(342)__Thalictrum thalictroides, commonly known as rue-anemone;

(343)__Thalictrum venulosum, commonly known as boundary meadow-rue;

(344)__Trichophorum clintonii, commonly known as Clinton's bulrush;

(345)__Triglochin gaspense, commonly known as Gaspe arrow-grass;

(346)__Trillium grandiflorum, commonly known as large white-trillium;

(347)__Trimorpha acris, commonly known as bitter fleabane;

(348)__Triosteum aurantiacum, commonly known as wild coffee;

(349)__Triphora trianthophora, commonly known as nodding pogonia;

(350)__Trisetum melicoides, commonly known as purple false-oats;