Having morphologically identical but physiologically distinct thalli within a species between which fertilization can take place but among which fertilization does not occur. Thus gametes released from the same plant do not fuse and self fertilization is prevented. Heterothallism is thought to be the most primitive form of sexuality and is found in certain of the lower algae and fungi, e.g. the green alga Ulothrix and the fungus Phytophthora infestans. It is also seen in certain higher plants that produce morphologically identical but self sterile gametophytes. Compare homothallic. |
