("Tsao quo" leads to either Amomum subulatum or to Amomum tsao-ko (or A. tsaoko). Thao qua leads to Amomum subulatum. The image here looks quite a lot like the seedpod of Amomum tsaoko. Alpinia alba Rosc. is nowadays Alpinia zerumbet, but given that the root of that is used, I haven't added a link to the A. zerumbet pages here. The latin synonyms given are all for Alpinia alba Rosc. -Henriette)
Hellenia alba, Willd.; Heritiera alba, Retz.; Lunguas vulgare, Koenig; Amomum medium, Loureiro, Fl. Cochinch.—The latter gives Tsao quo as the Cochinchina name, and Thao qua as the Chinese name of the plant.
Specimens of this fruit are in the Museum d'Histoire Naturelle of Paris, where they are labelled tsao-quo. For my specimens, I am indebted to Professor Guibourt, who calls the fruit the ovoid China cardamom (cardamome ovoide de la Chine).
The dried fruit is about the size and shape of a large nutmeg: it is ovoid, from ten to fourteen lines long, and from six to eight lines broad, rather rigid, striated longitudinally, yellowish-brown with a reddish tint [scarlet when recent, Koenig]. Seeds numerous, very large, pyramidal, brown externally, flavour and odour terebinthinate; albumen white, embryo yellow.
Grows in the province of Yu-nan. The seeds are aromatic, and are used by the natives as a condiment. They are said to be useful in intermittents. Koenig terms the plant galanga alba, and says it is much used among the Malays.