1108 



ELAPHOGLOSSUM 



ELECTRO-HORTICULTURE 



leathery, the surfaces somewhat viscid. Tropics of both 

 hemispheres. 



5. pilSsum, Moore. Blades flexuous, 6-8 in. long, 

 %in. wide, with tufts of star-like scales beneath; tex- 

 ture herbaceous. Mex. to Colombia. Chiefly of 

 botanical interest. 



BBS. Surface of Ivs. not scaly; texture leathery. 

 c. Margins of Ivs. thick, cartilaginous. 



6. simplex, Schott. Sterile blades 4-^12 in. long, 

 with a very acute point, the lower portion gradually 

 narrowed into a short, somewhat margined stalk. W. 

 Indies to Brazil. 



7. confdrme, Schott. Sterile blades 2-9 in. long, with 

 a bluntish point and wedge-shaped or spatulate base; 

 fertile Ivs. narrower. Tropics of both hemispheres. 



cc. Margins of Ivs. not thickened. 



8. flaccidum, Moore. Sterile blades 6-12 in. long, 

 with very acute point, the lower portion gradually 

 narrowed to the short stalk; fertile Ivs. on stalks 3-4 

 in. long. S. Amer. Of botanical interest only. 



AA. Veins uniting to form a network. 



B. Surface of Ivs. densely clothed with narrow scales. 



(Hymenodium.) 



9. crinitum, Christ. ELEPHANT-EAR FERN. Fig. 1387. 

 Blades 10-18 in. long, 4-8 in. wide, on densely scaly 

 stalks; fertile Ivs. smaller, on shorter stalks. W. Indies. 

 F.S. 9:936 (as H. crinitum). Omit sand in potting, 

 and avoid over-watering. 



1387. Elaphoglossum crinitum. 



BB. Surface of Ivs. mostly smooth, 6-15 in. long. 



10. reticulatum, Gaud. Blades on distinct stalks, 

 with wedge-shaped bases, 1J^ in. wide; veins forming 

 copious meshes. (Chrysodium.) Hawaiian Isls. Of 

 botanical interest only. 



11. gorgdneum, Brack. Blades tapering gradually 

 downward to the short stalks, 2-3 in. wide; veins form- 

 ing meshes only near the margin. (Aconiopteris.) 

 Hawaiian Isls. Of little decorative value. 



L. M. UNDERWOOD. 



R. C. BENEDICT.! 



ELATINE (Greek name of doubtful application). 

 Elatinacese. Small mostly glabrous creeping herbs, 

 probably annuals, of temperate and warm regions 

 (perhaps 10 species), sometimes used in bog- and water- 

 gardening. They root at the nodes, spreading along the 

 margins of streams and ponds. Lvs. opposite or verti- 

 cillate, mostly broad, entire: fls. minute and incon- 

 spicuous, mostly solitary in the axils; sepals and petals 



2-4, and stamens as many or sometimes twice as many; 

 styles or stigmas 2-4: pod 2-4-valved. The plants are 

 grown for their foliage cover. Four species are native 

 in the U. S. and Canada, but they appear not to be in 

 the trade. Abroad, E. macropoda, Guss., of the Medit. 

 region, is offered. Lvs. oblong, short-petioled : fls. 

 axillary and terminal, 4-merous, stalked: caps, half 

 shorter than the sepals. 



The family Elatinaceae is allied to the Hypericacese. 

 It comprises perhaps 25 species in many parts of the 

 world. The only other genus is Bergia, which differs 

 from Elatine in being terrestrial and in having 5-merous 

 fls. B. texdna, Seub., occurs in swamps and on wet 

 banks from S. 111. to Texas and Calif. The bergias are 

 apparently not in cult. L ft g > 



ELDER AND ELDERBERRY: Sambucus. 

 ELECAMPANE: Inula Helenium. 



ELECTRO-HORTICULTURE is a term used by 

 Siemens to designate the application of the electric 

 light to the growing of plants. The term is an unfor- 

 tunate one, since the use of electric light is not an 

 application of electricity to plant-growing, but is a 

 way of securing illumination. Any strong artificial 

 light hastens assimilation and thereby causes plants 

 to grow more rapidly. The practical questions to be 

 considered are, therefore, the expense of using the 

 light, and whether there are injurious elements in the 

 spectrum of the given light. 



The spectrum of the electric arc light is the spectrum 

 of carbon plus that of certain gases incident upon com- 

 bustion. The spectrum of the arc light is rich in rays 

 which light beyond the luminous part, and these rays 

 are very injurious to most plants. These rays of the 

 ultra-violet part of the spectrum are eliminated by a 

 plain glass, so that when the electric light is surrounded 

 by a globe, or when the light is hung above the roof of 

 the greenhouse, the injuries are reduced to a minimum. 

 Experiments at Cornell University showed that each 

 kind of plant behaves in its own way in the presence 

 of electric light. It is not possible to prophesy what 

 the results may be in a given species, without experi- 

 ment. A few plants, as tomatoes, cucumbers, melons 

 and carrots, seem to be very little affected either 

 injuriously or beneficially. Nearly all flowers are 

 hastened into bloom by the influence of the light, and 

 their colors are often brighter than under normal con- 

 ditions; but in very many cases they do not last so 

 long. The best results are secured if the light is applied 

 to the plants when they have reached nearly or quite 

 their full stature. If applied very early in its growth, 

 the plant tends to make flowers before it has attained 

 sufficient size. In floriculture, therefore, the practical 

 value of the electric arc light seems to be its influence in 

 hastening the flowering of certain plants in dark cli- 

 mates, or when plants must be had for a definite sea- 

 son. For example, if the light is applied to Easter lilies 

 for a month before their normal blooming time, the 

 period of bloom may be hastened four to ten days. 



Lettuce has shown greater beneficial results from the 

 application of the electric light than any other plant 

 with which careful experiments have been made. Let- 

 tuce which receives light from the arc lamp for half of 

 each night may be expected to reach marketable size 

 from one to two weeks before that which is grown in 

 normal conditions. 



As a rule, better results are secured when the light 

 runs only half the night. A common two-thousand 

 candle-power light has a marked effect on the growth of 

 many plants at a distance of sixty to even one hundred 

 feet. The incandescent light has a similar influence, 

 but not so marked. It has no injurious effect, however. 



As now understood, the application of the electric 

 light to the growing of plants is a special acceleration 

 to be used when the climate is abnormally cloudy or 



