HYD 



[499] 



HYG 



H. corda'ta (heart- leaved). White. July, Ca- 

 rolina. 1806. 



heteroma'lla (various - surfaced - leaved] . 4. 



White. Nepaul. 1821. 



horte'nsis (garden). 3. Pink. May. China. 



1740. 



ni'vea (snow - white - leaved) . 5. White. 



August. Carolina. 1786. 



glabe"lla (smoothish - leaved.) 5. 



White, green. July. 



quercifo'lia (Oak-leaved). 4. White. July. 



Florida. 1803. 



HYDEA'STIS. Yellow Eoot. (From 

 hydor, water ; referring to the marshy 

 places where it grows. Nat. ord., Crow- 

 foots [Ranunculaceee]. Linn., 13-Poly- 

 aiidria 1-Monogynia. Allied to Adonis.) 



Hardy herbaceous perennial. Division of the 

 root ; loam and peat ; moist situation. 

 H. Canade'nsis (Canadian). . Green. May. 

 North America. 1759- 



HYDRO 'LEA. (From hydor, water, 

 and elaia, oil ; referring to the marshy 

 habitat, and oily feel of the leaves. 

 Nat. ord., Hydrophyls [Hydrophylacesej. 

 Linn., 5-Pentandria 2-J)igynia.) 



Greenhouse herbaceous plants. Divisions, 

 cuttings, and seeds ; spinosa is a small aquatic, 

 growing best in peat and loam ; quadrivalvis 

 is also found in boggy places. 

 H. quudriva'lvis (four - divided) . Pale blue. 

 July. Carolina. 18U4. 



spino'sa (thorny). 1, Blue. South Ame- 



rica. 1791- 



HYDROME'STUS. (From hydor, water, 

 and mestos, half; referring to the plant 

 living in water during the rainy season. 

 Nat. ord., Acanthads [Acanthacese], 

 Linn., I-Didynamia 2-Angiospermia.} 



Stove evergreen shrubs. Cuttings of young 

 shoots, any time in spring and summer, in 

 sandy soil, and bottom heat ; peat and loam. 

 Summer temp., 60 to 80 ; winter, 48 to 55. 

 H. macula'tus (spotted). 2. Yellow. May. 

 Mexico. 1842. 



HYDROPE'LTIS. (From hydor, water, 

 and pelle, a shield; referring to the 

 floating shield-like leaves. Nat. ord., 

 Watershields [Cabombaceee], Linn., 

 \3-Polyandria 6-Polygynia.) 



A very neat little hardy water plant, well 

 worth growing by the edges of an aquarium, 

 round a mass of water lilies, its nearest allies. 

 Division ; marshy soil ; should be protected in 

 winter. 



H.purpu'rea (purple). Red. July. North 

 America. 1798. 



HYDROPHY'LLUM. Water-leaf. (From 

 hydor, water, and phyllon, a leaf. Nat. 

 ord., Hydrophyls [Hydrophyllace$e]. 



Linn.. 5-Penlandria l-Monogt/nia. Allied 

 to Monophila.) 



Hardy herbaceous perennials from North 

 America, Divisions and suckers ; rich loam 

 and peat ; in marshy situations. 

 H, appendicula'tum (appendaged-ea^ed). 

 Blue. May. 1812. 



Canade'nse (Canadian). . White. May. 



1759. 



Virgi'nicum (Virginian). . Blue. June. 



1739. 



HYDROWE'NIA. (From hydor, water 

 tainia, a band, referring to a triangular 

 band in the flower, secreting a liquid. 

 Nat. ord., Irids [Iridaceee]. Linn., 3- 

 Triandria I-Monogynia. Allied to Bea- 

 tonia.) 



A pretty half-hardy bulb, with the aspect of a 

 tigridia, and flowers like a fritillaria. Seeds, 

 sown when ripe, or kept and given a little heat 

 in the spring ; division of the off-sets ; light 

 rich sandy loam ; taken up and kept after the 

 foliage is decayed, and planted out the follow- 

 ing spring. If left in the ground, and covered 

 to protect from rains and frosts, the plants will 

 be stronger than if the bulbs were kept dry all 

 the winter. 



H. loba'ta (lobed-flotvered). !, Yellow, pur- 

 ple. May. Lima. 1843. 



'irwi " 



melea'gris (spotted) . 

 Mexico. 1837 



Yellow. July. 



HYGROMETER. An instrument for 

 ascertaining the quantity of moisture 

 in the air. Everything that swells by 

 moisture, and contracts by dryness, is 

 capable of being formed into one. 

 Every gardener, who has taken a cool 

 bunch of grapes into a hothouse well- 

 supplied with moisture, would, in the 

 grapes almost instantly being covered 

 with dew, see the principle upon which 

 the hygrometer acts. The colder the 

 grapes, the warmer the house, the more 

 the vapour contained in it, the sooner 

 would the dew be formed, and the more 

 plentiful its depositure. Pouring cold 

 water into a glass tumbler in similar 

 circumstances will be attended with a 

 similar result, dew will be deposited on 

 the outside of the glass; because, in 

 either case, the cold body condenses 

 the vapour in its neighbourhood, and 

 this is whatis called the dew point, being 

 that temperature at which moisture is 

 deposited from the surrounding atmo- 

 sphere upon any object of that particular 

 temperature. The drip in frames, 

 greenhouses, &c., is similarly caused. 

 The thermometer is the best instrument 



