Although the evidence against the retention of the species of _Lecythea_ (as the genus is named) amongst Fungi as true species, on the ground of di-morphism, is even stronger than against the group just illustrated, we cannot pass them altogether in silence, especially in a popular treatise. Those who are residents in town, and yet possess their little plot of garden-ground, with only two or three pet roses, may have had the misfortune of seeing them smothered with a yellow blight. This golden visitation, unwelcome as it is, may afford a subject for the microscope, and for a small space in this chapter. At first there will not appear to be any important difference between the spores of the yellow series of the last genus and those of the present; but a closer examination will reveal one important distinction, viz., the presence of colourless elongated, abortive spores. The species are not so numerous by half as those of _Trichobasis_, even when three anomalous forms are included, which species are included by some mycologists in two other genera. One very common rust of this group has already been alluded to (Plate II. fig. 37), and which is known botanically as _Lecythea Rosæ_. A similar one is found on the bramble, and another on the burnet. All these three species are produced at first on spots which are afterwards more or less occupied by the long, many-celled spores of the dark brown brands called _Aregma_ or _Phragmidium_, between which and the simple yellow spores of the rust almost every intermediate form may often be found in the same pustule. Thus, from the same mycelium as that of the rose rust, the rose brand is afterwards developed; whilst from the nidus of the bramble rust (Plate III. fig. 40) the bramble brand is also at length produced; and the successor to the burnet rust (Plate III. fig. 31) is the burnet brand. Besides these, a rust belonging to the same genus may be found on the leaves of the poplar, the spurge, and the common valerian, and two or three species on willows. It can scarcely have escaped notice, that the goat-willow is almost constantly afflicted with a rust on the under surface of the leaves (Plate VIII. fig. 160). This species will again come under notice as the summer spores of a truly dimorphous species.