Heteranthera pauciflora C.N. Horn, 2020

Heteranthera pauciflora C.N. Horn View in CoL , sp. nov. ( Fig. 4 View FIG ).

TYPE: VIRGINIA. CHARLES CITY CO.: shallow roadside pool NW of Harrison Point , 17 Aug 1938, Fernald & Long 9015 (HOLOTYPE: GH!; ISOTYPES: F!, LP, PH!) .

Inflorescentia cum 3–6 floribus pluribus intra spathum. Perianthium pallidum lavandulum. Perianthi tubus 8–10 mm longus; perianthi lobus 5.5–7.3 mm longus;antherae in stamine laterali 0.6–1 mm longae,anthera in stamine centrali 1.3–1.9 mm longa.

Leaf blade rounded, acute to obtuse at apex, 3.5–5.2 cm long, 4.2–6.5 cm wide. Spathe 3.0– 5.7 cm long. Inflorescence 2.2–4.3 cm long with 3–7 flowers, 3–5 of which are within the spathe. Perianth tube 8–10 mm long; perianth lobes pale lavender to white, 5.5–7.3 mm long; lateral stamens 2–2.9 mm long, the anthers 0.6–1 mm long; central stamen 4.2–4.8 mm long, the anther 1.3–1.9 mm long. Seeds 0.8–1 mm long, 0.4–0.5 mm wide, with 9–11 wings. Chromosome number unknown.

Phenology.— Flowering July to November. Inflorescences developing in one day. Individual flowers open about three hours after dawn and wilt in early afternoon. Most commonly flowers do not elongate out of the spathe and are thus self-pollinated.

Distribution ( Fig. 3 View FIG ).—Freshwater marshes and river margins typically under tidal influence, sea level to 20 m; USA, New Jersey to North Carolina.

Representative specimens. U.S.A. DELAWARE.[New Castle Co.]: near Wilmington, Canby 8491 ( KANU). MARYLAND. Cecil Co.: White Swan Lake, ca. 2 mi SE of Chesapeake City, Long 41098 ( PH). NEW JERSEY. Burlington Co.: South Branch of Pensaulan Creek , 0.25 mi S of Fork Landing, Trudell s.n. ( PH). Camden Co.: along Delaware River off of NJ 543 in Pennsauken, Horn8614 (GH, MEXU, MICH,MO,NASC, NY, UNA). Gloucester Co.: Mathews Brook, West Woodbury, Long 26588 ( PH). Salem Co.: 2 mi NW of Pedricktown, Fogg 7915 (GH, PH). NORTH CAROLINA.Bertie Co.: US 17 at Connie Creek,Roanoke River Swamp, Radford 5968 (NCU,SMU). Martin Co.: shallow pool edge of cypress-gum swamp near Welch Creek on US 64 at Washington Co. line, Radford 4586 (NCU, NY). Pasquotank Co.: 4.4 mi S of Weeksville, Ahles 48126 (FLAS, NCU, UC). Perquimans Co.: 1.6 mi NE of Bethal, then 1.2 mi E on dirt road, Ahles 48024 (NCU, SMU). PENNSYLVANIA. Philadelphia Co.: League Island Park, Hass s.n. ( PH). VIRGINIA. Gloucester Co.: Beaverdam Lake off rt 606, Horn 12489 (GMUF, NY, UNA,WILLI); Newport News City, 200 ft from Mulberry Island Rd., Fort Eustis, Appler 828 (NCU,WILLI).

These plants have rounded leaves with an obtuse to slightly acute apex and the flowering axis is only about as long as the spathe and the perianth is a pale lavender color. The inflorescence has 3–6 flowers and typically only the terminal flower projects beyond the terminus of the spathe, so it may open ( Fig. 1d View FIG ).