Hippuris x lanceolata Retz.
Hippuridaceae, mares tail family.
Obs. 3: 7. 1783.
Hippuris tetraphylla L.f. x Hippirus. vulgaris L
Vegetative morphology. Plants perennial herbs; 10–50 cm high; aquatic, with leaves in whorls of (5-)6-(-7), often growing on damp saline mud. Ground-level or under-ground stems horizontal (and semi-horizontal stems, rooting in soft substrates); rhizomatous (but rhizomes are rarely found on herbarium specimens); elongate, or compact. Aerial stems erect; not conspicuously jointed; glabrous. Leaves heterophyllous, or not heterophyllous (plants growing on damp mud often appear to have only one form of leaf); distributed along the stems; whorled (usually 6 leaves per whorl); existing for a single season or less. Petioles absent. Blades (5–)20–80 mm long. Blades somewhat fleshy (emerged leaves); lanceolate, or oblanceolate. Blades adaxial surface glabrous. Blades abaxial surface glabrous.
Reproductive morphology. Inflorescence spicate; axillary. Pedicels absent. Flowers small, less than 5 mm in diameter or length; zygomorphic (very reduced). Perianth absent. Flowers unisexual. Stamens 1. Gynoecia inferior. Carpels monomerous (pseudo-monomerous); 1. Placentation apical. Fruit indehiscent.
Chromosome information. 2n = 32. Zhukova (1982 north eastern Asia); Arohonka (1982 Finland). Supposed basic chromosome number of family 4x.
Notes. In North Norway this entity occurs quite independent of its
proposed parents, rarely in company with any of them and distinctly outside the
range of H. tetraphylla. I have seen the same in some W Alaskan sites. It
is intermediate but I am not yet fully convinced of its hybrid origin. (Elven).
In the 1970ies the Belgian L. Vanhecke revised much of the northern
materials of Hippuris. Two sheets from the Arctic Islands in HbO were
re-determined as H. lanceolata, from Southampton Island (Coral Harbour,
leg. W.J. Cody, 24/7 1948) and from Baffin Island (Mallik island, leg.
R.Hainault & R.Norman, 10/8 1970). We have re-examined these specimens and
rather consider them as modifications of H. vulgaris, possibly in
brackish waters.
The images illulstrating this taxon were taken at Coral
Harbour Southampton Island.
Illustrations. • Plants in habitat.. Stranded plants growing in a sedge- Dupontia meadow. Nunavut, Southampton Island, Coral Harbour. Aiken and Brysting, 01063. CAN. • Plants in habitat.. Stranded plants growing at the edge of a dried-up tunrda pool. Nunavut, Southampton Island, Coral Harbour. Aiken and Brysting, 01065. CAN. • Close-up of plants.. Stranded plants growing at the edge of a dried up tunrda pool. Aerial stems erect and in flower. Nunavut, Southampton Island, Coral Harbour. Aiken and Brysting, 01065. CAN. • Close-up of plant.. Flowering and fruiting aerial stem. The male flower consists of a single anther, seen on the left hand side. The female flower consists of a single ovary with a single style that terminates in an unmodified stigma. Most ovaries in the picture have been fertilized and are developing into fruit. Nunavut, Southampton Island, Coral Harbour. Aiken and Brysting, 01063. CAN. • Close-up of flowering stem.. Female flowers each with a single wine reddish ovary that has a single syle and an unmodified stigma. The linflorescence develops from the base upwards. Nunavut, Southampton Island, Coral Harbour. Aiken and Brysting, 01063. CAN. • Close-up flowering whorl.. Whorl of leaves of leaves with flowers in the axils of the leaves. The male flowers consist of a single stamen with a pinkish filament (far right) and a globose brown anther that opens on the sides to shed yellow pollen. The thin recurved, structures are withered style-stigmas covered with pollen that was received earlier. Nunavut, Southampton Island, Coral Harbour. Aiken and Brysting, 01063. CAN. • Close-up of leaves in whorls of six.. Hippuris lanceolata. Close-up of whorls Whorls with mostly six, comparatively broad and subacute leaves. Norway: Finnmark, Porsanger, Viekker, brackish marsh. 13/7–1984. Photo: R.Elven. Voucher in HbTROM.
Cite this publication as: ‘S.G. Aiken, M.J. Dallwitz, L.L. Consaul, C.L. McJannet, L.J. Gillespie, R.L. Boles, G.W. Argus, J.M. Gillett, P.J. Scott, R. Elven, M.C. LeBlanc, A.K. Brysting and H. Solstad. 1999 onwards. Flora of the Canadian Arctic Archipelago: Descriptions, Illustrations, Identification, and Information Retrieval. Version: 29th April 2003. http://www.mun.ca/biology/delta/arcticf/’. Dallwitz (1980) and Dallwitz, Paine and Zurcher (1993, 1995, 2000) should also be cited (see References).
