It must not be forgotten that twenty-eight species of rust belonging to this genus are now recorded as occurring in Great Britain. Some of these have yellow or yellowish spores; the rest have the spores of a decidedly brown colour. One of the most attractive of the yellow-spored species is that which appears on the groundsel (_T. Senecionis_), and a good notion of its external appearance may be gained from our figure (Plate VII. fig. 145). It is not always to be found without searching closely, for in some localities we have found it very sparingly, whilst elsewhere—as, for instance, on Wandsworth Common—we have met with it as soon or as late as there were groundsel leaves for it to grow upon. No spot or change in the appearance of the upper surface of the leaves indicates the presence of the parasite beneath; this is, however, often betrayed by the golden-yellow streaks which appear on the stem. Many a time and oft the boys in the semi-rural districts about town have marvelled and questioned each other concerning the reason why, in gathering “groundsel” for the little bird at home, we should be so particular, and pass so many promising plants, plucking here and there a leaf, and seldom collecting one which they consider eligible for the purpose. Collectors of minute fungi must expect to overhear occasionally even hints touching their sanity from those who, without the remotest idea of their mission, think they must be slightly “wrong in the head” to gaze so narrowly and intently, amongst nettles, groundsel, grass, or dry leaves, and only take an occasional fragment of a rotten stick, or two or three sickly leaves, carefully deposit them in their wallet, hat, or pocket, and then “move on.”