Symptoms and signs of the fungal infection, if manifested at all, only occur on a specific tissue or site of the host tiller, where the fungal stroma or sclerotium emerges. The stroma (pl. stromata) is a mycelial cushion that gives rise first to asexual spores (conidia), then to the sexual fruiting bodies (ascocarps; perithecia). Sclerotia are hard resting structures that later (after incubation on the ground) germinate to form stipate stromata. Depending on the fungus species, the host tissues on which stromata or sclerotia are produced may be young inflorescences and surrounding leaves, individual florets, nodes, or small segments of the leaves. Young stromata are hyaline (colorless), and as they mature they turn dark gray, black, or yellow-orange. Mature stromata eject meiotically derived spores (ascospores), which are ejected into the atmosphere and initiate new plant infections (horizontal transmission). In some cases no stroma or sclerotium is produced, but the fungus infects seeds produced by the infected plant, and is thereby transmitted vertically to the next host generation. Most "Epichloë" species, and all asexual species, can vertically transmit.