Leaf smut

Sori in leaves, as round or angular spots 2–6 mm diam or, by confluence, much larger, at first white, later brown and dried, often confluent. 

Spores solitary or often in small groups, globose, ovoid to polyhedrally irregular, 12–20 × 11–15 µm, pale yellow to brownish yellow; spore wall 1–4 (–5) µm thick, 2-layered; inner layer of uniform thickness, the outer layer varying from thin, inconspicuous and regular to considerably thickened and uneven.