Kummerowia striata vs Kummerowia stipulacea

Kummerowia striata (Japanese clover) and Kummerowia stipulacea (Korean clover) are two similar species with tiny pink flowers that bloom in late summer or early fall.

The leaves of each species are similar, but there are slight differences. The leaves of K. striata are a little narrower than those of K. stipulacea. Also, the margins of the leaves of K. stipulacea have conspicuous hairs, especially on younger leaves, whereas the leaves of K. striata have smaller, inconspicuous hairs or none at all.

Both species have stems with appressed hairs (i.e. the hairs are pressed closely against the stem, rather than standing up). However, the direction that the hairs are appressed is different between the two species. In the pictures below, the direction of growth of the plant is from left to right.

In the case of K. striata, the appressed hairs are retrorse, meaning that they point downwards, opposite the direction of growth.

The opposite is true of K. stipulacea. Its appressed hairs are antrorse, i.e. appressed upwards.