AND GENEKAL HORTICULTURE. 



183 



HEA 



requires a certain amount of attention, which 

 must be given at the right time, or no satis- 

 factory results can be expected. 



Heating by Hot Water. This is now the 

 method in use in nearly all well-appointed 

 green-house structures. But little detail need 

 be given, as this branch of heating is done 

 almost exclusively by firms who make a special 

 business of it, and who generally understand 

 the construction and requirements necessary 

 in heating, better than those who employ 

 them usually do ; but there are some points 

 which it is perhaps as well to state. In any 

 section of the country where the thermometer 

 falls below zero, if a green-house, ten feet 

 high, twenty feet wide, and 100 long, is to be 

 heated by hot water, and a night-temperature 

 of sixty degrees is required, there should be 

 not less than eight "runs" of four-inch pipes 

 running the length of the house ; if fifty de- 

 grees are required, six "runs " of pipe ; if forty 

 degrees, four "runs " of pipe. The styles of 

 boilers in use are so varied that we forbear to 

 give any one in particular a preference here. 

 If estimated by the glass surface, one foot in 

 length of four inch pipe is necessary for every 

 three and one half square feet of glass surface, 

 when the temperature is at ten degrees below 

 zero, to keep a temperature of fifty degrees in 

 the green-house. For small green-houses, or 

 such as are attached to dwellings, a simple 

 contrivance known as the Base-burning Water 

 Heater is very convenient. The boiler takes 

 up no more room than an ordinary stove, and 

 the fire requires no more skill or attention 

 than any ordinary base-burning stove, being 

 fed by coal from the top. It can be left with 

 safety ten or twelve hours without any atten- 

 tion. At present prices, a Base-burning Water 

 Heater with pipes sufficient to heat a green- 

 house 10x50 feet, will cost about $200, or 

 for twice that size about $350. 



Heating by Steam. Few green-houses are as 

 yet heated by steam, though the cost of con- 

 struction is much less, and it is also claimed 

 that there is greater economy in fuel ; but 

 though we have had green-houses heated for 

 the past forty years, both in Europe and 

 America, by hot water, steam heating for 

 glass structures has made little progress. It 

 has been successfully done, however, both in 

 Philadelphia, Chicago, and the vicinity of New 

 York, and experiments with it on a large 

 scale are now being tried in several parts of the 

 country. We have but little doubt that in 

 erecting green-houses on an extensive scale 

 at one time it is economy to use steam heat- 

 ing ; but nearly all such structures are progres- 

 sive, a few being added each year, and the 

 heating by the ordinary hot-water pipes is as 

 yet believed by the uninitiated to be the safer 

 mode. It must be some such reason as this, 

 whether right or wrong, that has so long 

 caused green-houses to be heated by hot water 

 in this age of steam. 



Hebecla'dus. From hebe, pubescence, and 

 klados, a branch, in reference to the hairiness 

 of the young shoots. Nat. Ord. Solanacece. 



A genus of perennial herbs or sub-shrubs, 

 natives of western tropical America. H. 

 biflorus is an interesting green-house shrub 

 with handsome drooping purple flowers. It was 

 introduced from the Andes of Peru in 1884, 



IIED 



and is propagated by cuttings of the half- 

 ripened wood. 



Hebecli'nium. A genus now included with 

 Eupatorium. 



He'ctea. Named after J. H. G. Hecht, a Prus- 

 sian counsellor, who died in 1837. Nat. Ord. 

 Bromeliacece. 



A genus of pretty green-house plants, closely 

 allied to Dyckia. The leaves are long, spiny, 

 recurved, and crowded. They are all natives 

 of Mexico. H. Ghiesbrechtii is the most orna- 

 mental and desirable species. 



Hedeo'ma. Mock Pennyroyal. From hedeoma, 

 the Greek name of Mint. Nat. Ord. Labiatce. 

 The only species of interest in this genus is 

 H. pulegioides, the American Pennyroyal, com- 

 mon in open, barren woods and fields. It has 

 the taste and odor nearly of the true Penny- 

 royal (Mentha Pulegium) of Europe. 



He'dera. The Ivy. The name appears to be 

 derived from hedra, a Celtic word, signifying 

 a cord ; and the English name, Ivy, is derived 

 from iw, a word in the same language, signi- 

 fying green, from its being always green. 

 Nat. Ord. Araliacece. 



This well-known plant is what botanists 

 call a rooting climber ; that is to say, its 

 stems climb up trees, walls, sides of dwell- 

 ings, or any other suitable object which pre- 

 sents a sufficiently rough surface for their 

 roots to take hold of ; as, unless this is the 

 case, the Ivy, whenever it is rendered heavy 

 by rain or snow, falls down. Whenever, 

 therefore, Ivy is wanted to cover smooth, 

 newly-plastered walls, the Ivy should be 

 nailed against them, or secured with copper 

 wire. The Ivy is remarkable for undergoing 

 a complete change in its leaves when it flow- 

 ers. The barren, or creeping Ivy, which trails 

 along the ground, and roots into it, rarely 

 flowers, and its leaf is deeply cut ; but the 

 tree Ivy, or flowering part, rears itself on 

 high, so as to be fully exposed to the light 

 and air,and the leaves become of an oval shape. 

 H. Canariensin, the giant, or Irish Ivy, as it is 

 sometimes called, though it is a native of the 

 Canaries, is hardier and grows much faster 

 than the common kind ; but the variegated 

 kinds are tender, and grow much slower. Ivy 

 requires a deep and somewhat light soil, into 

 which its roots can penetrate easily; and 

 when grown for any purpose in pots or boxes 

 it should be abundantly supplied with water. 

 Ivy is useful in all cases where a naked space 

 is to be covered with green in a short space 

 of time ; and it is particularly valuable in 

 town gardens, as it will bear the smoke and 

 want of pure air in cities better than most 

 other plants. It should, however, in ali close 

 and crowded situations, be abundantly sup- 

 plied with water, and occasionally stringed 

 over the leaves. The gold and silver varie- 

 ties are very beautiful, especially the former, 

 when grown against the chimney of a dwell- 

 ing-house or green-house ; but they, like 

 nearly all variegated-leaved plants, are more 

 tender, and require a higher temperature 

 than the plain green-leaved kinds. Increased 

 freely by cuttings. 



Hedera'ceee. A name given to the Nat. Ord. 

 Araliacece. 



Hedge Bindweed. Calystegia sepium. 



Hedge-hog. Ranunculus arvensis. 



