&f)e Ereagurp af 380tang. 



606 



and growing generally in fresh water. 

 Movements of granules may be seen in the 

 cells of many of the plants. ValUsneria 

 spiralis is found in the south of Europe. 

 Two species of this genus occur in New 

 Holland. The leaves of Hydrocharis morsus 

 ranee are mucilaginous and astringent. 

 Anacharis Alsinastrum has become na- 

 turalised in many parts of Britain. There 

 are nineteen genera, and about thirty-six 

 species. Examples: Udora, ValUsneria, 

 Stratiotes, Hydrocharis. [J. H. B.] 



HYDROCHARIS. A small floating aqua- 

 tic, giving name to the order Eydrochari- 

 dacea?, and distinguished by the following 

 characters : ovary six-celled ; stigmas six, 

 wedge-shaped, two-cleft ; stamens six to 

 nine. H. morsus ranm, or Frogbit, is an 

 elegant little plant, inhabiting ditches, 

 ponds, and the still back waters of rivers. 

 It Increases by floating horizontal runners 

 which shoot out to a considerable length ; 

 from the joints descend tufts of long, 

 scarcely branched roots, which penetrate 

 deep into the mud. m From the same points 

 issue pendulous le'af-buds, supported on 

 long footstalks ; each of these buds is 

 composed of two leaf-like scales, folded 

 together and curiously enveloping the 

 embryo leaves of the future plant. The 

 leaves are stalked, kidney-shaped, entire; 

 the flowers of three delicate white petals, 

 rise several in succession, from a pellucid 

 membranous sheath, and bear the stamens 

 and pistils on separate plants. This is one 

 of the most desirable plants for the fresh- 

 water aquarium. French, Morene ; German, 

 Froschbiss. [C. A. J.] 



HYDROCHLOA. A genus of grasses be- 

 longing to the Oryzece. H. carolinensis, 

 with Zizania aquatica, the Canada rice, con- 

 stitute the genus Hydropyrum. The name 

 is also given to another group of grasses 

 synonymous with Gli/ceria. [D. MJ 



HYDROCLEIS. A genus of aquatic plants, 

 belonging to the Butomacea?, growing in 

 tropical America. They have the leaves all 

 radical, cordate ovate. The flowers are on 

 simple scapes, large, yellow, with the three 

 inner perianth segments petaloid and de- 

 ciduous ; the three outer green and per- 

 sistent; they have numerous stamens, and 

 from six to nine carpels. Limnoeharis, as 

 now restricted to L. Plumieri, differs in 

 bavins? fifteen to twenty carpels, and an 

 umbel of flowers. [J. T. S.] 



HYDROCOTYLE. An extensive genus 

 of umbelliferous plants, mostly herba- 

 ceous and of humble growth, but some 

 approaching shrubs in habit, difficult of 

 discrimination, and possessing little in- 

 terest except for the scientific botanist. 

 The only native species, H. vulgaris, com- 

 mon Pennywort, is one of the few British 

 plants which have peltate leaves. The plant 

 bears an ill name from being considered, in 

 conjunction with two or three other bog 

 plants, the fruitful cause of rot in sheep, 

 an unfounded accusation, for it possesses 

 no noxious properties, and sheep more- 1 



| over refuse to eat it. German, Wasser- 

 nabel. [C. A. J.] 



HYDRODICTYE^, HYDRODICTYOK 

 An order and genus of green-spored Algce, 

 remarkable at once for beauty and singu- 

 larity of structure. The plant, when full- 

 grown, resembles a long purse, consisting 

 of a beautiful regular network of threads. 

 These threads contain a mass of endo- 

 chrome which is ultimately resolved into 

 minute zoospores ; these arrange them- 

 selves, within the articulation which gave 

 them birth, into polygons, in such away as, 

 when united, to form a network, which 

 gradually increases till it resembles the 

 parent plant ; each joint, therefore, of the 

 network gives rise to a new individual. 

 This singular mode of development is 

 without example in other orders. The 

 other genera usually ascribed to this order 

 are probably related to Anadyomene. Hy- 

 drodictyon utriculatum is found in fresh 

 water, though rarely, in several parts of 

 Etu'ope, and has long been known as grow- 

 ing every year in the pond in the Old Bo- 

 tanic Gardens at Cambridge. It has also 

 been found in the United States. [M. J. B.] 



HYDROGLOSSUM. A genus of climbing 

 ferns of the Schizcea group, the exact ana- 

 logues of Lycjodium inhabit and fructifica- 

 tion, but differing therefrom in having 

 netted instead of free veins, the venules 

 anastomosing in from two to four series 

 of unequal obliquely-elongated hexagonal 

 areoles. The species are but few, and are 

 found in the Pacific Isles, Madagascar, and 

 Mexico. [T. MJ 



HYDROLEACE^E. A name given by 

 Brown to the plants now included in the 

 order Hydrophyllacece. [J. H. B.j 



HYDROLEA. A genus of Hydrophylla- 

 cew, containing several species common in 

 America, and rare in Asia and Africa. They 

 are marsh plants, often armed with axillary 

 spines, and bearing alternate entire leaves, 

 and axillary or terminal blue flowers, 

 which have a calyx of five persistent 

 sepals, a rotate campanulate corolla, five 

 stamens inserted in the tube of the corolla, 

 and a two-celled ovary with many anatro- 

 pal ovules, attached to fungous placentas. 

 The capsule is two-celled with numerous 

 small striated seeds. The leaves of R. 

 zeylanica are bitter; in India they are 

 beaten into pulp, and applied as a poultice 

 to ill-conditioned sores with a beneficial 

 effect. [W. CJ 



HYDROGERA VASA. The spiral threads 

 inside a spiral vessel ; formerly supposed 

 to be tubes conveying fluid. 



HYDROPELTIS. A genus deriving its 

 name of Water-buckler from the shape 

 of the leaves. It is included among the 

 Cabombacece, and differs from Cabomba in 

 the numerous thread-like stamens, and 

 the equally numerous whorled, somewhat 

 fleshy carpels. H. -purpurea, called also 

 Brasenia peltata, is a curious little water 

 plant, with floating peltate oval leaves, 

 and purple flowers, on the end of some- 



