A Gladiolus flanaganii corm usually grows five leaves annually. There are also a few cataphylls at the base. They are small scale leaves sometimes seen, grown from the corm, coloured green and sometimes flushed pink. The tallest one of them is about 4 cm tall. The plant clearly also develops clumps of corms producing in unison as in the photo.
Four of the main leaves are basal, half as long to as long as the inflorescence. The lance-shaped, acutely pointed blades are from 7 mm to 14 mm wide, green in picture. The midribs are moderately thickened, glassy from translucence. There are sometimes two more thickened veins flanking the midrib, while the leaf margins develop little thickening. The leaves are wavy on some plants.
The fifth leaf emerges from the stem, in the upper third of it. It is smaller than the others, channelled and its base sheathes the stem (Goldblatt and Manning, 1998; iNaturalist).