1877.] 



AND HORTICULTURIST. 



89 



classes it with insect work. Still we know how 

 easy it is to be mistaken, and have therefore 

 suggested to those who have faith in the nisect 

 origin of the disease, to send the specimens to 

 compelent Entomologists for the insect's identi- 

 fication. Mr. Chas. Henderson has generously 

 undertaken this good work, and from two of the 

 recipients of specimens — Prof. Riley and Mr. J. 

 StaufFer — we have replies. Mr. StaufFer's views 

 were directly opposite to Prof. Riley's, so Ave 

 thought best to send it to Prof. Riley, that he 

 might review his own if necessary. As thus far, 

 Mr. Stauffer is the only naturalist that we know 

 of who takes the insect view, we have thought it 

 but fair to give him the first hearing, and below 

 appears Prof. Riley's comment: 



" After a close inspection of the diseased leaves 

 left with me, I obtained fresh ones from my neigh- 

 bor, Mr. Hensel, as in getting rid of the frag- 

 ments of moss in which the leaves were packed, 

 I had to disturb the surface more or less of the 

 leaves. I have also made a close inspection of 

 the fly — an Aphidian, belonging to Mr. Walsh's 

 genus, Callipterus. Honey tubes short, subulate, 

 Antennae long, seven-jointed, discoidals of the 

 front wings equally thick, carries the wings hori- 

 zontally folded ; in this latter respect it agrees 

 with the winged of the Phylloxera (vastatrix, 

 vitifoliee). These in their larvsel state infest the 

 root in Winter, and it seems it is proved that 

 they also infest the leaves in the Summer season. 

 The Callipterus is certainty the small black- 

 fly noticed around the Verbenas, and deposits 

 its eggs, as I captured them from the leaf, Janu- 

 ary 15, 1877. 



" Now, as to the rust. Their larvae when 

 hatched, (the minute mites mentioned,) deplete 

 the leaf and empoverish the juices, and cause 

 the leaf to bliglit, unless the plants are in such 

 good soil and healthy vigor, as to be able to bear 

 this depletion, and then no fungus will follow, 

 and the plant may escape. But when the sto- 

 mata or bi-eathing pores of the leaf are inter- 

 fered with and the juices abstracted, the leaf be- 

 comes depauperated and forms a fit nidus for 

 the fungus. So Mr. Henderson is wrong to say 

 that, ' the insect is the consequence, and not the 

 cause, of the disease.' Mr. Brinton's views are 

 more accurate. I have found well defined fun- 

 gus and made accurate drawings of them from 

 the mildew in its white powdery form, or first 

 stage, when the leaf is yet green. By compari- 

 son with quite a number of forms illustrated, it 

 approaches the mycelium and sporadic branches 



of the Cistopus candidus. Figured by Smee, in 

 his Garden, p. 366, he says many plants are at- 

 tacked with spots of white rust, on the leaves, 

 arranged in a circular manner. The mycelium 

 creeps through the cellular tissue of the plants, 

 and after a time gives rise to zoospores or moving 

 bodies to perpetuate the species, adding, ' I be- 

 lieve that in all these cases the plant is previously 

 pierced by an Aphis.' One word as to zoospores : 

 so long as they are free they have indeed a great 

 likeness to infusoria, but as soon as they have 

 found a fit resting place all trace of motion 

 ceases, and their oftspring comforts itself as a 

 vegetable; this is scientifically demonstrated, 

 but zoospores never turn to Aphids or the like. 

 The disease on the Heliotrope differs ; here the 

 root of the hair becomes enlarged, and a yel- 

 lowish matter is secreted; this turns dark, and 

 then the bulb-like base cracks open and dis- 

 charges sporules. I first considered the whole as 

 a fungus, but if mycelium is formed under the 

 epidermis and enters into the base of the tubu- 

 lar hairs, and produces its sporules, then, this is- 

 a fungus of a totally new kind to me, but its 

 cause may arise from the same source— poverty 

 or depletion." 



Prof. Riley says :— " I have not time now to 

 further investigate the Verbena rust, but feel 

 morally sure that it is a fungus disease. The 

 "black-fly" referred to in my answer to Mr. 

 Henderson is a Diplosis. There are several 

 Aphids affecting both leaves and roots of Verbe- 

 nas, but they have nothing to do with the rust." 



Since the above was in type, a note from Prof. 

 Farlow tells us that the Verbena rust is a fungus, 

 and that its name is Erysiphe Verbena? of 

 Schweinitz. It will therefore be an old acquaint- 

 ance to mycologists. 



Zelkova " Crensta."— Prof. Sargent writes :— 

 "My authority. for Zelkova crenata is Planchon, 

 in DecandoUes Prodromus, the last botanist who 

 has worked Ulmacese comprehensively. He does 

 not even allow Abelicea as a genus, so I suppose 

 we must retain Zelkova at least until another 

 volume of the Genera Plantarum appears. 



"But what a pity we cannot retain Michaux's 

 Planera Richardi ; a much pleasanter and more 

 easily remembered name ; but this does not make 

 much difference so long as the tree is planted, so. 

 I hope you will get some of the grafts Mr. Price 

 so kindly offers, and see what can be done with 

 them. 



" Typographical errors are not very pleasant 

 for the editor, I will allow, but how about his 



