Basidia and basidiospores developing from overwintered telia of Melampsora larici-epitea on Salix burjatica 'Korso' Overwintered telia on fallen willow leaves germinate to produce yellowish basidia and basidiospores (left) in spring. Meiosis occurs during teliospore germination and formation of basidia. The basidia become 4-septate and each produces 4 basidiospores. Right picture shows basidiospores formed on a basidium. Haploid basidiospores infect larch and form spermogonia/spermatia.