Other species of _Puccinia_ are found on Composite plants, but with none of these is the present fungus likely to be confounded, if regard be had to its peculiar habit. The leaves, for instance, of the common knapweed (_Centaurea nigra_) are often sprinkled with the small pustules of the centaury brand (_Puccinia compositarum_, Sch.); these generally occupy the under surface of the lower radical leaves (fig. 67); occasionally a few of the pustules appear on the upper surface. We have not often found this fungus in the neighbourhood of London on the leaves of the knapweed, but, on the other hand, we have encountered it very commonly on those of the saw-wort (_Serratula tinctoria_). The spores are oval, scarcely constricted, and not attenuated in either direction (fig. 68). Other Composite plants than those above named are liable to attacks from this parasite. In our school-days we remember to have spent many a stray half-hour digging for “earthnuts,” under which name we, as well as our elders and betters, knew the tubers of _Bunium flexuosum_. Not then, nor for many years after, did we notice, or regard if we did notice, the distorted radical leaves and leaf-stalks, and the blackish-brown spots, which reveal the cause in the presence of a brand, or parasitic fungus, of this genus (_Puccinia Umbelliferarum_, DC.), which is extremely common on this, as well as some other allied plants. If any spot is searched where this plant grows in any profusion, before the flowering stalks have made their appearance above the surrounding grass, this _Puccinia_ will be readily found by the twisted, contorted, sickly appearance of the infested leaves (fig. 71), the petioles of which are often swollen and gouty in consequence. The sporidia are shortly stalked, and generally very much constricted (fig. 72). The species found on the stems of the hemlock, and also that on Alexanders (_Smyrnium Olusatrum_), are distinct; the spores of the latter being covered with tubercles or warts (figs. 55, 56). During a botanical ramble through Darenth Wood in April of the year just passed away, in some parts of which the sanicle abounds, we found the bright glossy leaves of this singular and interesting plant freely sprinkled with the pustules of a _Puccinia_ (_P. Saniculæ_, Grev.), which is not at all uncommon on this, but has not hitherto been found on any other plant. Dr. Greville, of Edinburgh, was the first to describe this, as well as many other of our indigenous minute Fungi. For many years he has toiled earnestly and vigorously at the lower cryptogams, as evidenced by his “Scottish Cryptogamic Flora,” published in 1823; and yet his continual additions to the records of science show him to be earnest and vigorous still.