BOTANY WITH BASICS OF HYDROBOTANY (AQUATIC PLANTS OF UKRAINE) - B.Ye. Yakubenko - 2011

X. SEED PLANTS

Water-starwort Family (Callitrichaceae)

Small annual aquatic or marsh plants with slender, mostly branched stems. Leaves entire, sessile, with one to three longitudinal Veins, opposite, the upper ones often gathered into a floating rosette. Flowers tiny, unisexual, lacking a perianth, solitary in the leaf axils, either subtended by two membranous bracts or bractless; lower flowers pistillate, with a sessile superior four-locular Ovary and two styles; upper flowers staminate, consisting of a single stamen on a long filament with a bilocular anther. Floral formula: pistillate - ♀ G₍₄₎, staminate - ♂ A₁. Fruit dry, leathery.

The family comprises a single genus with 25 species distributed worldwide, except for Africa. The flora of Ukraine is represented by five species.

Autumnal Water-starwort (Callitriche hermaphroditica L., C. autumnalis L.). An annual plant, 5-30 cm tall, entirely submerged in water; tenagophyte, hydrophile, hydrochore. Stems slender, brittle, profusely branched at the base, densely leafy toward the apex. Leaves sessile, opposite, translucent, lanceolate, dark green, single-veined, widened at the base and narrowed at the apex; upper leaves never forming a rosette, 6-15 mm long, 2 mm wide. Flowers solitary, unisexual or bisexual, without bracts. Fruits are capsules, 1.5 (3) mm in diameter, nearly sessile, their lobes keeled and broadly winged. Blooms within the water Column from June to September. Propagated by seeds.

Grows in lakes, stagnant water bodies, and slow-flowing rivers, frequently forming extensive submerged beds. Occurs sporadically throughout almost all of Ukraine, except for Crimea.

Blunt-fruited water-starwort (Callitriche cophocarpa Sendtner., C. polymorpha Loennr.). An annual plant, 5-45 cm tall; tenagophyte, hydrophile, anemochore, hydrochore, zoochore. Stems filiform, slightly flattened. Leaves light green, dimorphic: lower leaves (submerged) linear, 1-2 cm long, 1-3 mm wide; upper leaves (floating) suborbicular-ovate, up to 4 mm in diameter, with a midrib and two lateral veins.

Floating leaves are gathered in rosettes of 10-14. Flowers solitary, axillary, unisexual or bisexual, with membranous bracts and a reduced perianth. Bracts sickle-shaped, hooked at the apex. Styles thick, sturdy, 4-6 mm long, persistent in fruit. Fruit a flattened-globose capsule, 1.2-1.5 mm wide, with lobes lacking a keeled margin. Blooms in the surface water layers or above the water surface from June to September. Propagated by seeds.

Grows in the shallows of small rivers, ditches, backwaters, and in bogs sparsely distributed across almost the entire Ukraine. Depending on local habitat conditions, the plants exhibit significant variation in leaf shape and size, as well as stem height.

Hooked water-starwort (Callitriche hamulata Kutz. ex W.D.J. Koch.). An annual plant, 5-20 cm tall; tenagophyte, hydrophile, hydrochore. Rhizomes filiform, straight. Stems slender, 5(20)-50(80) cm long. Leaves dimorphic: lower (submerged) leaves semi-translucent, linear, deeply notched at the apex, 1-2.5 cm long, 0.5-1.2 mm wide, opposite; upper (floating) leaves suborbicular-ovate, dark green, gathered into an emergent floating rosette.

Flowers unisexual, one to two per leaf axil. Styles slender, filiform, 1-3 mm long, reflexed downward, dropping off shortly after flowering. Bracts sickle-shaped, hooked at the apex. Fruits are capsules, broadly ovate or flattened-globose, 1-2 mm wide, with broadly or narrowly membranous-winged lobes. Blooms in the surface layers of water from June to October. Propagated by seeds.

Grows along banks with soil waterlogging, in shallow coastal areas, bogs, lakes, oxbows, and ditches; occasionally found in Polissya and the Forest-Steppe regions.

Spring water-starwort (Callitriche verna L., C. palustris L.). An annual plant 50-150 cm tall. Stem ascending, rooting at the nodes, slender, branched. Leaves bright green and subopaque, dimorphic: lower (submerged) leaves linear with a single vein; upper (floating) leaves obovate with three longitudinal veins, forming a rosette. Flowers axillary, unisexual or bisexual, with slightly curved or sickle-shaped bracts lacking a hook at the apex. Styles straight, falling off long before the fruit ripens. Fruit a capsule, obovate, rounded at the base, with narrowly margined lobes. Blooms from June to October. Propagated by SHOOT fragments and seeds.

The plant is extremely variable and known in numerous forms.

It serves as a food source for gastropod Mollusks of the family Lymnaeidae.

Grows in ditches, small lakes, ponds, shallow rivers, and bogs. Very common in the western regions of Ukraine, Polissya, and the Forest-Steppe, less frequent in the Steppe, and occasionally in Crimea.

Pond water-starwort (Callitriche stagnalis Scop.). An annual plant, 5-50 cm tall; tenagophyte, hydrophile, anemochore, hydrochore, zoochore. Stem slender, branched. Leaves bright green, opaque, all obovate, or the lower leaves linear with a single vein, and all others with three or more veins. Upper leaves form a floating rosette of five to eight leaves. Flowers solitary, sessile, unisexual, rarely bisexual. Fruits are capsules, 1.5-2 mm in diameter, flattened-globose, with broadly membranous-winged lobes. Styles persist for some time in fruit. Blooms in the surface layers of water or above the surface from May to September. Propagated by seeds.

The plant is grazed by certain crustaceans, such as aquatic isopods (water hoglice) and amphipods.

Grows in stagnant water bodies, including mountain forest lakes, as well as in damp and marshy habitats; occasionally found in Zakarpattia, forest and forest-steppe regions, and mountainous Crimea.