108 



THE GARDENERS' CHRONICLE. 



[March 30, 191?. 



been in the collection of Mr. Gratrix for some 

 years, but this is the first occasion he has shown 

 it ;it a London exhibition* The flowers are of 

 fine shape, and the ground clear white, with 

 markings on the sepals and petals of light violet 

 colour. The lip is broader than in most forms, 

 white, and with reddish purple markings in front 

 of the yellow crest. 



THE NATURE OF PARASITIC FUNGI. 



THEIR INFLUENCE UPON THE HOST 



PLANT. 



(Continued from p. 183.) 



In the germination of the spores of the late 

 blight Potato fungus, the contents of the conidia 

 breaks up into a number of minute bodies, which 

 are mobile and are able to move about in water. 

 \fter a very short period, however, these 

 swarm-spores become stationary, and their walls 

 thicken, until they finally germinate by produc- 

 ing the typical infection tube. 



There are numerous fungi which produce both 

 summer and winter spores. The powdery milde v 

 of Grapes, scab of Pears and Apples, all produce 

 two forms of spores. The ascospores are nearly 

 always winter spores. The teleutospores of 

 rusts, the resting or egg spores of the Perono- 

 sporse, which eause the downy mildews, are not 

 ascospores, though typical winter spores. The 

 summer spores serve the purpose of a rapid 

 propagation of the fungus, while the winter 

 spores are responsible for carrying diseases over 

 the winter. Very rarely may summer spores be 

 carried through the winter alive, owing to their 

 feeble protection and short life. The winter 

 spores are produced in conceptacles, which are 

 exceedingly well protected. They adhere firmly 

 to the substratum on which they have been pro- 

 duced, or they are imbedded therein. This is of 

 great importance to the practical grow T er. By 

 destroying all leaves, dead fruits, and other plant 

 refuse, he is able to get rid of vast numbers of 

 winter spores, and thus is able to safeguard his 

 orchards in the best way possible. To illus- 

 trate this point, let us briefly consider the case 

 of the common fruit scab fungus. For some 

 considerable time the summer spores only of this 

 fungus were known. It received at first the 

 generic name Fusicladium, which is even now 

 sometimes used, though erroneously. Xo winter 

 spores were known until some ten years ago, 

 when they v re discovered in spring on the dead 

 leaves and old fruits. When this stage was found 

 the fungus received the name Venturia. The 

 discovery of the winter stage is very important, 

 as it gives us a valuable clue to the way in which 

 the fungus may be attacked. The successful de- 

 struction of this most common orchard disease 

 is now a very simple matter. Spraying in spring 

 to kill the first crop of spores, and the destruction 

 of old rubbish in autumn successfully prevents 

 the appearance of this and many other diseases. 



Those interested in the investigation of plant 

 diseases have long recognised the immense im- 

 portance of the careful study of the life history 

 of disease-causing fungi. Though progress may 

 be slow, I am of the opinion that the careful 

 investigation of fungus diseases and insect pests 

 is one of the most important features of the suc- 

 cessful raising of fruit. Errors in the treat- 

 ment of diseases, false methods of cultivation, 

 the attempt to grow varieties unsuitable to the 

 locality are points which are responsible for a 

 large proportion of the losses in fruit-growing. 

 But as it 



the form of 



as it is, fruitgrowers are willing to 

 pay such unnecessary taxes in 

 losses instead of combining their efforts to pre- 

 vent disasters, and thus double and treble their 

 fruit crops and increase their revenue. These 

 remarks are not empty words. I do not believe 

 in indulging in destructive criticism. We have 

 evidence along these lines which will prove that 

 freedom from disease in orchards has 



some 200 trees, which bore not a single sound 

 fruit — they were one and all black with scab ! 

 Now this orchard is a menace to the locality. 

 From it the disease is carried for miles all over 

 the country. What is the use of spraying your 

 orchards while your neighbour remains idle ? 

 Ten trees in an orchard affected with scab will 

 suffice to keep you busy spraying ; whereas going 

 into that neighbour's orchard and pulling down 

 his trees would be the best self-help, though 

 I doubt whether, strictly speaking, it is 

 quite legal. //. T. Gilssow, Dominion Botanist, 

 Ottawa, Canada. 



(To be continued.) 



SARRAGENUS OUT-OF-DOORS. 



Deep in a little ravine on the hillside — shel- 

 tered from the wind, but open to the warm sun, 

 and refreshed by the ceaseless trickle of a little 

 mountain spring — this is the ideal position for 

 the Sarracenia, and it is in just such a place as 

 this that w r e have established, at Leonardslee, 

 a splendid clump of this plant. The best time to 

 see it is in May and June, when the effect of the 



Insects are first attracted to the flower bv its 

 brilliant colouring, and soon find a further in- 

 ducement to remain, in the honey, on which they 

 feed. They proceed from the rim of the cup to 

 the inside, and penetrate to the bottom. Here 

 however, they remain ; for the inside of the cup 

 is covered by innumerable short hairs, all point- 

 ing downwards, so that although the insects find 

 it perfectly easy to enter, to depart is impossible. 

 The final fate of the insects varies in the different 

 varieties of Sarracenia. In some cases, the bot- 

 tom of the cup is filled with water — sometimes as 

 much as two or three inches — and the insect is 

 drowned. In other cases, it is simply starved to 

 death, or suffocated beneath the other victims. 

 Some of the flowers catch an astounding number 

 and variety of insects. It is interesting to take 

 a " pitcher " which has been developed for some 

 time, pluck off the head, and count and sort the 

 victims contained in the cup. In one case, a 

 mass of insects was found, three inches 

 deep, composed of butterflies, woodlice, beetles, 

 cockroaches, earwigs, countless numbers of flies, 

 both large and small, and even several wasps ! 



For a long time after the insectivorous habits 

 of the plants were observed, it was not known 



Fig. 86. 



[ Photograph by C. P. RaffilU 



CYTISUS DALLIMOREI (c. SCOPARIUS VAR. ANDREANUS X C. ALBUs) \ 

 *• FLOWERS ROSE-COLOURED. 



in- 



creased the harvest of good and perfect fruit 

 considerably. Becently I visited an orchard of 



well-developed "pitchers" and blossoms is very 

 fine. Planting should be done at once, and a few 

 hints on this subject may be useful. 



When preparing the ground for the plants, the 

 top spit should be taken off, and laid in, grass 

 downwards. Over the upturned sods lay a mix- 

 ture in equal quantities of peat and Sphagnum- 

 moss ; the plants should then be put in, and the 

 ground round them made firm with a further 

 supply of the peat and moss mixture. They may ' 

 be slightly shaded, until growth begins, with 

 some branches of evergreen. 



The ideal position for these plants has been 

 described above, but they succeed in any damp 

 but sunny place — such as a bog or marsh. Dro- 

 seras also do well, if planted among the Sarra- 

 cenias; so does the Cotton Grass (Eriophorum 

 angustifolium), which presents an extremely effec- 

 tive contrast with the fine crimson blossoms of 

 the "insect-trap." 



The process by which the Sarracenias allure 

 and capture thousands of unwilling prisoners is 

 a most interesting one. A kind of sweet mois- 

 ture nearly resembling honey is constantly 

 exuded from the glands found on the blade, and 

 covers the parts round the aperture of the cup. 



what advantages were derived from it ; but it is 

 a fact that the plant obtains nourishment from 

 the decomposed bodies of the victims, and that, 

 though it would be possible, by artificial means, 

 to prevent ingress of the insects, the plant would 

 probably suffer. Naturally, from our point of 

 view, the habit is an objectionable one, as the 

 smell of the decomposing insects is most un- 

 pleasant. W. A. Cook, Leonardslee Gardens, 

 Horsham. 



CYTISUS DALLIMOREI. 



In fig. 86 is reproduced a bed of the pretty 

 rose-coloured Broom raised from Cytisus 

 scoparius variety Andrianus crossed w« 

 C. alba, the white Broom. It was raised by Mr. 

 Dallimore when in charge of the Arboretum at 

 Kew, with another of the same cross having 

 bright-yellow flowers like the common Broom. 

 C. Dallimorei was exhibited at the Temple Show, 

 1910, and received an Award of Merit from the 

 Floral Committee. A full description of tno 

 plant was given by Mr. R. A. Rolfe in Garden** 

 Chronicle, July 18, 1910, p. 397, in an artici* 

 entitled " Cytisus Dallimorei and Heredity. 



