Potamogeton schweinfurthii Bennett (1901: 220)

Abbasi, Shabnam, Afsharzadeh, Saeed, Dinarvand, Mehri & Wiegleb, Gerhard, 2017, Synopsis of Potamogetonaceae in Iran with supplements to the Flora Iranica and a new identification key, Phytotaxa 311 (1), pp. 1-21 : 11

Potamogeton schweinfurthii Bennett (1901: 220) ( ‘Schweinfurthii ᾿), Fig. 11

Perennial, rhizome slender, stem slender to robust, terete, unbranched. Leaves dimorphic, submersed leaves sessile to shortly petiolate, narrowly lanceolate to oblong-elliptical, 500–1700 mm long, 20 mm wide, the upper ones partly petiolate, yellow-green to bright green, 7-veined, minutely denticulate in immature state, cuneate at base, acute to mucronate at apex, stipules not fused, 25–75 mm long, membranaceous; floating leaves petiolate, often absent, oblong to elliptical or ovate, 43–130 mm long, 10–20 mm wide, 2–6 times as long as wide, yellow-green or dark green, with a reddish tinge, 11–21-veined, cuneate to rounded at base, obtuse to acute at apex; petiole 40–70 mm long. Spike 25–35 mm long, peduncle 25–35 mm long, as thick as stem. Tepals 1 mm, anthers 0.8–0.9 mm long. Carpels 4, fruits 3 mm long. Stele of trio to oblong type, endodermis of U-type, interlacunar bundles present, subepidermal bundles present. This species is distinguished from P. gramineus Linnaeus (1753: 127) by the unbranched stem and the petiolate submersed leaves. It is distinguished from P. lucens Linnaeus (1753:126) by the narrower submersed leaves (20 mm vs. 4.5 mm, respectively) and the presence of floating leaves. It is distinguished from both species by the almost less thickened peduncle.

Worldwide distribution: —S Europe, the Azores, Africa, Madagascar, Mascarene Islands, West Asia ( Palestine).

Distribution in Iran: —West.

Flowering time: —From spring and summer.

Specimen examined: — IRAN. Lorestan: Gahar Lake, 2335, 13 July 2010, Dinarvand 8760 (Herbarium of the Research Center of Agriculture & Natural Resources of Khuzestan!) ; Azerbaijan: Ardebil to Khalkhal, Neor lake , 1450 m, 15 July 1991, Zehzad, Jamzad, Izadpanah & Taheir 70524 ( TARI!) .

Figures

FIGURE 11. P. schweinfurthii a. cross section of stem (Scale bar: 100 μm, objective lens 4), b. morphological shape.