The tiny, brown fruits of Mentha longifolia are stacked around the top parts of the spent inflorescences. Now dry and densely clustered, they probably still contain some seeds. The photo was taken in April, well past the plant’s summer bloomtime.

The inflorescence of M. longifolia consists of a long, cylindrical spike of small, stalkless white to lilac flowers. The flowers are whorled at closely spaced nodes. Each flower has a four-lobed corolla and becomes about 4 mm long. A full, many-flowered spike is about 10 cm long and 12 mm in diameter (Manning, 2009; Pooley, 1998; Roberts, 1990).