This photo shows the tiny, brown fruits of Mentha longifolia stacked around the top parts of the spent flowering stalks. Now dry and densely clustered, they probably still contain some seeds. The photo was taken in April, well past the plant’s summer bloom-time.
The inflorescence of M. longifolia in bloom consists of a long thin spike of whorls of small, stalkless white to lilac flowers. Each flower has a four-lobed corolla. A flower is about 4 mm long; a full flower spike comprising many flowers is about 12 mm in diameter (Manning, 2009; Roberts, 1990).