I remember those little red beans, crimson red disc-like beans 红珠仔.. in a popular game played by young girls mostly in the southern, tropical countries.
A poem was written about these red beans by a poet in Tang Dynasty 唐朝诗人 王维
http://hanyu.iciba.com/wiki/132439.shtml#1 (my English version follows):
红豆生南国 In southern kingdom they grow
春来发几枝 Sprouting abundance in spring
愿君多采撷 Wish thou would pick aplenty
此物最相思 Most lovesake are these beans
"...唐朝诗人王维咏颂红豆的这首名诗流传至今，仍然被人们广为传诵，真可谓千古绝唱。鸟有相思鸟，树有相思树，豆也有相思豆。
相传古代有位少妇，因思念出征战死于边塞的夫君，朝夕倚于门前树下恸哭，泪水流干了，眼里流出了血，血泪染红了树根，于是就结出了具有相思意义的红色小豆子..."
With the help of an old school mate, hotfoong (whose interests extend from photography to electronics to quantum physics to meteorology to astronomy to multiverse to pursuits of passion and compassion..), I was able to recall the species' botanical name: Adenanthera pavonina, also known as 海紅豆, 孔雀豆 or 相思豆:
http://www.hktree.com/tree/adenanthera_pavonina1.htm
http://en.wikipedia.org/wiki/Adenanthera_pavonina has meaningful passages about 相思豆 tree:
"This tree is useful for nitrogen fixation, and it is often cultivated for forage, as a medicinal plant, and as an ornamental garden plant and urban tree. The beauty of the seeds, their use as beads and for necklace, and their nourishing qualities.. ..The wood, which is extremely hard, is used in boat-building, making furniture and for firewood..."
As romantic as it is indigenously meaningful also known by its Malay name, saga, and this part is what I really like:
"...in India, the seeds have been used as far back as history records as units of weight for fine measures, of gold for instance. The Malay name for the tree, saga, has been traced to the Arabic for 'goldsmith'.."
A tree of substance and ornament.
A produce for health and utility.
A unit of fine measure of gold.
