Suleiman has little axial tilt, therefore no seasons;
bluejack grows all year round in the cool, dry Uplands;
hunters and gatherers pick it, then regularly rendezvous with nomadic herders who barter for the bluejack;
a caravan takes it to the city about twice a month;
Solar, i.e., the Solar Spice and Liquors Company, exchanges Technic goods for bales of bluejack;
four times a Terrestrial year, a Cynthian ship collects the bluejack;
the Cynthians deliver letters, journals, books, tapes and news;
scientists study the planet, hoping to win reputations;
for the factors, like Dalmady, the post is a first step on a career ladder;
plantations would be more efficient but too costly to be profitable.
Poul Anderson goes into considerable detail about how an interstellar economy works.
