Tetragonia tetragonoides (Pall.) Kuntze

Family: Aizoaceae
English: New Zealand Spinach
Japanese: ツルナ [Tsuruna]

This vine creeps over course-sandy beaches. The small yellow flowers slower grow and harden into seeds. The leaves have good texture and are a staple in wild vegetables, although I find I grow sick of the more-acidic-than-true-spinach taste.

References:
九州野山の花 片野田逸朗,2004：南方新社
米倉浩司・梶田忠 (2003-)　「BG Plants 和名－学名インデックス」（YList），http://ylist.info（ 2019年8月13日）