Coleogeton (H. G. L. Reichenbach) D. H. Les & R. R. Haynes

Herbs, rhizomatous; turions absent; tubers absent or present. Stems terete, nodes without oil glands. Leaves submersed, alternate, opaque, sessile, linear to setaceous, caniculate, turgid, acute at base, margins entire, apex obtuse to acute, veins 1--5; stipules not tubular, adnate to base of leaf blades for 2/3 or more of stipule length, extending past adnation as a free ligule. Inflorescence a capitate or cylindrical spike, submersed; peduncles flexible. Flowers with gynoecium of 4 carpels. Fruit abaxially rounded, with or without beak, turgid; embryo with less than one full coil. x = 13.

Species ca. 6 (4 in the flora): nearly worldwide.

The stipules of Stuckenia are adnate to the blade for two-thirds to nearly the entire length of the stipule. The few species of Potamogeton with adnate stipules have the adnation less than half the length of the stipule, in fact, mostly less than 4 mm. Submersed leaves of Potamogeton are translucent, flat, and without grooves or channels, whereas those of Stuckenia are opaque, channeled, and turgid.

Les and Haynes (1996) proposed elevating Potamogeton subgenus Coleogeton to the generic level, retaining the name Coleogeton. They chose Potamogeton pectinatus L. as the nomenclatural type. They, however, overlooked that Börner (1912) had previously published Stuckenia and had cited P. pectinatus, making the generic name Coleogeton superflous. Holub (1997) pointed out that Stuckenia was the correct name and made the appropriate specific combinations.

Selected references: Börner, C. 1912. Botanisch-systematische Notizen. Abhandl. Naturwiss. Ver. Bremen 21: 245--282; Holub, J. 1997. Stuckenia Börner 1912 -- the correct name for Coleogeton (Potamogetonaceae). Preslia 69: 361--366; Les, D. H. & R. R. Haynes. 1996. Coleogeton (Potamogetonaceae) a new genus of pondweeds. Novon 6: 389--391; Moore, E. 1913. The potamogetons in relation to pond culture. Bull Bureau Fish. 33: 251--291 + pls. xxii--xxxix; Reveal, J. L. 1977. Potamogetonaceae, pp. 24--42. In A. Cronquist, et al., Intermountain Flora, Vol. 6. Columbia Univ. Press, New York; St. John, H. 1916. A revision of the North American species of Potamogeton of the section Coleophylli. Rhodora. 18: 121--138; Thorne, R. F. 1993. Potamogetonaceae, pp. 1304--1308. In J. C. Hickman, ed., The Jepson Manual. Univ. California Press, Berkeley.

Stuckenia pectinata