Pl. sori. [mod.L., ad. Gr. σωρός heap.]
1. Bot. A cluster of capsules or spore-cases on the under surface of fern-leaves.
1832. Lindley, Introd. Bot., I. iii. 196. In a third tribe the sori occupy the whole of the under surface of the frond.
1857. T. Moore, Handbk. Brit. Ferns (ed. 3), 8. The part of the vein on which the sorus is seated.
1876. Harley, Royles Mat. Med., 360. Sori elliptical, imbedded in the substance of the thallus, concave on one side.
2. A similar formation in algæ, lichens or fungi.
1842. Penny Cycl., XXII. 266/2. The term sorus is sometimes applied to mere collections of spores or granules, as seen in many Algæ, of which Delesseria alata and D. sinuosa are examples.
1874. Cooke, Fungi, 38. The pustules, or sori, break through the cuticle in a similar manner.