74 



Till': ORCHID WORLD. 



fj;inu;iry, 1915. 



OlilTUARY. -Wc res:;Tet to record tht^ denth, 

 which took i)lace on December i/th ult., of 

 Mr. W. B. Latham, for thirty-five years curator 

 of the Birmingham Botanic Gardens. His 

 name will be rememliered by ryi)ri]iedium 

 Lathamianum (Spicerianum x \ illosum) raised 

 Ijy him m 1888. 



U SI U 

 SXENOf.T.OTTIS LONGIFOLIA. — This pretty 

 South African j)lant merits greater attention 

 lhan generally gix'en, for its graceful and 

 erect many-flowered spikes are seen at their 

 best during the dull days of December. The 

 blooms are light mauve-purple, with a singular 

 five-toothed lip ; a pure white form has been 

 discovered, but remains very rare. One of 

 the finest batches of plants it has been our 

 pleasure to see is m the collection of Col. 

 .Stephenson R. Clarke, C.B., Borde Hill, 

 Cuckfield, Sussex, where many of the spikes 

 have attained the height of 3 feet, and carry 

 innumerable flowers. These plants are under 

 the care of Mr. E. Johnson, who attributes 

 much of his success to the fact that the 

 tuberous roots are not dried off directly the 

 ])lants have finished flowering, but are kept 

 moderately moist until the new growth 

 appears above the surface, when more water 

 is applied, chiefly to the compost, although 

 occasional spraying of the foliage is found to 

 be beneficial. Some growers place the pots 

 on a shelf as soon as flowering time is over, 

 and there leave them in a dry state until the 

 spring, much in the way of Thunia treatment, 

 but this method does not yield anything like 

 the satisfactory results seen in the Borde Hill 

 collection. The plants being of a terrestrial 

 nature require a compost of fibrous loam with 

 the addition of a little leaf mould. 



Orchifj Fungus. — The Journal of the 

 Royal Horticultural Society, Vol. XL., Part IL, 

 contains a report of the lecture given by 

 IVof. J. B. Farmer, D.Sc, F.R.S.," on the 

 Plant in Relation to its Biological Environ- 

 ment, from which we abstract the following- 

 note : — "A study of the relation of the 

 higher plant to various fungal species is full 

 of promise, both from a practical and a 



theoretical point of view. The cultivation of 

 Orchids has been facilitated by the discovery 

 of the general nature and mode of infection 

 of the germinating seedling with the so-called 

 symbiotic fungus. One of the most interesting, 

 and from a theoretical point of view 

 important, instances of the relation of an 

 Orchid with a fungus is that of the Japanese 

 species Gastrodia elata. We are fully 

 acquainted with its remarkable life history, 

 and it is one of the very few instances in 

 which we are sure of the identity of the 

 infecting fungus. Gastrodia is a terrestrial 

 sjiecies which forms underground tubers. 

 These only produce flowers when they have 

 been infected with a rhizomorph of Agaricus 

 (ArmiUaria) melleus, which is often parasitic 

 on the trees amongst which the Orchid 

 grows. There are many theories (or rather 

 h)'potheses) as to how the association of the 

 root and fungus to form a mycorrhiza is 

 brought about, and as to the relation to each 

 other which subsists between the two 

 symbionts. But the examples that have been 

 investigated leave no room for doubt that the 

 relation is essentially one of parasitism. The 

 degree of infection, however, is checked by 

 the root, in some way not as yet fully 

 understood. For the present it will suffice to 

 say that, while in many cases the fungus 

 seems to thrive, but fails to penetrate the 

 deeper tissues of the root; in others it invades 

 the whole plant without, however, doing it 

 any harm. In others, again, certain tissues of 

 tne host plant have obviously and definitely 

 the power of destroying it after it has 

 infected them and thriven for a while in their 

 interior. But the mycorrhizal association itself 

 js always beneficial, and often indispensable. 

 I he influences which enable a parasite to 

 obtain entrance into the body of its host plant 

 are at least two-fold in nature. First, there 

 is the attraction, which directs the attack, and, 

 secondly, there is the actual method of 

 penetration. It is probable that in all cases 

 the sense of direction is given by some 

 substance that exudes from the host plant, 

 and that this serves as the means of 

 attraction which determines the direction of 

 growth towards it on the part of the parasite." 



