Jane 1, 1876. ) 



JOURNAL OF HORTICULTUEE AND COTTAGE GAEDENER. 



421 



WEEKLY CALENDAR. 



SYBINGING. 



' practice in tlio art of liorfciculture is 60 

 diametrieally opposed to Nature as that of 

 forcibly ejecting water from a syringe or 

 engine against tlie under side of tlie foliage 

 of plants. To arrive at a necessity or other- 

 wise for syringing plants on the under sur- 

 faces of the leaves it may be desu'able to 

 point to the diversity which exists between 

 plants cultivated in the open ground and 

 those in an artificial climate under glass. 

 Those in the open air have in addition to rain that depo- 

 sition of moisture termed dew, neither the one nor the 

 other having access to the under side of the leaves ; and 

 that there is design in the leaves being formed and die- 

 posed for throwing off the water either outwardly or 

 inwardly we may safely conclude, and that this design 

 is for the benefit of the plant. Were moisture most 

 beneficial to plants when applied to the under side of the 

 leaves we should not have had such provision made by 

 Nature for preventing it being conveyed to those parts. 

 I am cognizant of the deeper colour of the upper surface 

 of the leaves being the cause of that surface always 

 being exposed to the light, which is abundantly confirmed 

 by reversing the surface of the leaf, and the leaf so 

 reversed regaiuing its original position. Upon this di- 

 rection of the leaves the presence of the stomates, hairs, 

 and elevated veins on the under sides of the leaves are 

 principally due; for when by accident or design the 

 surface of the leaves are reversed the under surface being 

 turned uppermost acquire all those characters in conse- 

 quence of inversion — the previously under side thickening 

 its epidermis to enable it to withstand solar light, whilst 

 the previously upper surface now that it is turned down- 

 wards has the power of forming stomates ; whilst with 

 the margin of the leaves directed towards the earth and 

 the sky the two surfaces are then equally furnished with 

 stomates. 



Now the stomates exert considerable influence in plant 

 economy ; the upper surfaces of the leaves have a much 

 tliicker epidermis than the under, thickening in propor- 

 tion to the amount of evaporation caused by the solar 

 rays, the thickness being increased when it is necessary 

 to control evaporation more powerfully than usual ; but 

 to farnish leaves with the means of parting with super- 

 fluous moisture when the epidermis offers too much 

 resistance to permit its passage, or when in dry weather 

 fluid is not derived in sufficient quantity from the soil, 

 the stomates open, especially at night, admitting atmo- 

 spheric moisture. The power of leaves to absorb atmo- 

 spheric moisture has been questioned, but is now generally 

 accepted : — How otherwise could a flagging plant be re- 

 stored to freshness by sprinkling its leaves with water ? 

 The power to absorb moisture appears to be more power- 

 ful in the under than upper surface of the leaves, though 

 the power is unquestionably possessed by both surfaces. 

 Greater evidence of the leaves' power to absorb moisture 

 we could not possibly have than that of plants in droughty 



No. 792.— Vol. SXX.. New Seeiib. 



weather flagging by day and recovering their freshness at 

 night. I am prepared for being met by this being ac- 

 counted for by the cause of evaporation being withdrawn, 

 the plant deriving snfiicient moisture from the soil to 

 restore its freshness at night which it could not maintain 

 beneath the solar rays ; but the fact remains that the 

 same plant placed in a dry room does not recover its 

 freshness, which it does when placed in a moist at- 

 mosphere. 



It is certain that plants absorb moisture by their leaves, 

 and we are warranted in affording to growing plants 

 a moist atmosphere, and water over the foliage at night 

 approximating to light showers of dew ; but water driven 

 against the under side of the leaves is foreign to nature, 

 and certainly cannot act beneficially except by freeing 

 the plants of insects lodging on the under surface of 

 the leaves, for the stomates are most abundant on the 

 under side of the leaves, and to dash water against them 

 must be to close them or to fill them with water, pre- 

 venting the gradual absorption of atmospheric moisture. 

 Had Nature intended the stomates to absorb water other 

 than in the state of vapour surely they would have 

 been more abundant on the upper than lower surface of 

 a leaf ; and that they are not designed to absorb water in 

 its crude state we may, I think, infer from plants with 

 floating leaves having no stomates on the under side, 

 whilst in the case of a plant with the margins vertical, or 

 nearly, as that of an Iris, the stomates are about equal on 

 both surfaces of the leaf. Some leaves have the power of 

 abstracting moisture or nutriment by the upper surfaces of 

 the leaves more powerfully than the under, as the Drosera 

 and Diontea ; but generally atmospheric moisture is more 

 powerfully absorbed by the under than the upper surface 

 of the leaves of plants. 



The unanimous advice given by the best and most 

 experienced practitioners of securing a moist atmosphere 

 is proof conclusive that a moist atmosphere is an es- 

 sential for free healthful growth ; but that actual sy- 

 ringing acts otherwise than mechanically in freeing the 

 upper surface of the leaves of dust and the under of 

 insects is subject of doubt, inasmuch as the very general 

 practice of syringing Vines has been supplanted by the 

 better practice of affording atmospheric moisture by 

 sprinkling and generating moisture by evaporation from 

 warmed surfaces. 



Except in the matter of syringing plants on the 

 under surface of the leaves we approach as nearly as it 

 is possible to do by an artificial process to nature in the 

 furnishing of atmospheric moisture ; but that it is neces- 

 sary to drench the foliage of nine-tenths of the plants 

 grown under glass morning and afternoon is not so clearly 

 distinguishable. The practice of sprinkling overhead two 

 or three times a-day is no more necessary for many 

 plants when making fresh growth than is depriving them 

 of every semblance of atmospheric moisture when it is 

 completed. Drenching as occasionally resorted to for the 

 purpose of freeing the upper surface of the foliage from 

 dust and the under of insects may be desirable, but 

 that there is any benefit resulting to the plants so sub. 



No. Hli.— Vol. LV., Old Series. 



