Sterigma
![The sterigmata are the slender extensions that connect the spores (green) to the basidia (red).](/Images/godic/202502/13/Basidie-23519.jpg")
![The sterigmata remain as small projections on twigs of Picea and Tsuga after the leaves have fallen.](/Images/godic/202502/13/Picea_glauca_twig_Denali_NP_AK3519.jpg")
In biology, a sterigma (pl. sterigmata) is a small supporting structure.
It commonly refers to an extension of the basidium (the spore-bearing cells) consisting of a basal filamentous part and a slender projection which carries a spore at the tip. The sterigmata are formed on the basidium as it develops and undergoes meiosis, to result in the production of (typically) four nuclei. The nuclei gradually migrate to the tips of the basidium, and one nucleus will migrate into each spore that develops at the tip of each sterigma.