26o 



The great part which the bark parenchyma, with its abnormal phenom- 

 ena of stretching, plays in the formation of the bark shows that this de- 

 velopment of rotten bark in the moor pine is related to the "hark refuse" of 

 the elm and distinguishes both cases from the actual tan disease (see page 

 215) in which the formation of full cork has the upper hand, as in the many- 

 layered lenticels. 



Horticultural Moor Plants. 



The growers, probably because of their study of the natural habitat of 

 our heather plants, have used for imported Ericaceae the soil in which our 

 Calluna grows splendidly: — i. e., heath moor. The properties of Sphagnum 

 peat, thus ascertained, have made this a desired article in trade. Its ad- 

 vantages consist in its loosening properties. The results of experiments in 

 cultivating Ericaceae led to the mixing of the so-called moor soil with 

 heavier nutritious soils as a loosening substance. In this way, the moor soil 

 has been introduced as a necessary element in soil mixtures for most of the 

 tiner horticultural plants. Since no standard was known, however, for a 

 good moor soil, many kinds came into trade, with the growing demand. Some 

 were either over rich in raw humus, or resembled the character of the 

 meadow moor. The dark color of the meadow moor led to the incorrect 

 opinion that a very nutritive earth was present. The results of this mis- 

 conception were very evident. The complaints of gardeners about acid heath 

 soils are almost universal and the degeneration of many favorite plants, such 

 as the so-called new Holland, or "Cape plants," could not be arrested. 



Where meadow moor was used as an admixture in soils for potted 

 plants, its properties quickly manifested themselves. In a dry condition, 

 this moor soil seems to be easily pulverized, decomposing into a powder, or 

 remaining crusty. When wet, however, it becomes smeary and cements the 

 other particles of soil into dense masses with a poor air content. Since 

 meadow moor heats greatly, the upper layers in the flower pot dry out easily, 

 become lighter colored and suggest to the gardener that the whole ball 

 of soil is dry and should be watered. Here is the danger, for meadow moor 

 deceives as does no other soil. If such moors be investigated in nature, the 

 smeary condition is found directly under the dusty surface, a few centi- 

 metres deep, since the very binding substance retains the water unusually 

 long. Potted plants are often killed by a lack of oxygen at the roots, even 

 if the humic acids are not taken into consideration. These, however, play a 

 disasterous role and often cause the injury arising in many cases from the 

 use of loose, fibrous marsh soil. Sphagnum peat is the most beneficial be- 

 cause the leaf is so constructed that it makes a very porous soil, giving rapid 

 moistening and as rapid an aeration of the soil in the pot. The excellent re- 

 sults obtained in growing orchids with sphagnum are well known. Good re- 

 sults will only be had with fibrous moor soils, full of fragments of Vaccin- 

 ium and other moor plants and taken from forest soils, if the raw humus is 



