_Nicotiana rustica_, the native tobacco of North America, was found to be inferior to that grown in the Spanish Colonies. Botanists state that _Nicotiana rustica_ had a much greater nicotine content and sprouted or branched more than that cultivated today. William Strachey, one of the first colonists, gave the following description of the native plant grown in 1616: It is not of the best kynd, it is but poore and weake, and of a byting tast, it growes not fully a yard above the ground, bearing a little yellowe flower, like to hennebane, the leaves are short and thick, somewhat round at the upper end.... In 1611 Rolfe decided to experiment with seed of the mild Spanish variety. He persuaded a shipmaster to bring him some tobacco seed from the Island of Trinidad and Caracas, Venezuela; and by June, 1612, tobacco from the imported seeds was being cultivated at Jamestown. On July 20, 1613, a Captain Robert Adams landed the _Elizabeth_ in England with a sample of Rolfe's first experimental crop. In England, this first shipment was described as excellent in quality, but it was still inferior to Spanish tobacco. In 1616 Rolfe modestly asserted, "no doubt but after a little more triall and expense in the curing thereof, it will compare with the best in the West Indies." The success of Rolfe's experiment was soon apparent. In 1617, 20,000 pounds of tobacco were exported from Virginia, and in the following year the amount doubled. Tobacco did not become the chief staple owing merely to the successful attempts by Rolfe to produce a satisfactory smoking leaf. As has been noted, there was a ready market for tobacco in England before the settlers landed at Jamestown. A second important cause was the fact that tobacco was indigenous to the soil and climate of Virginia. Tobacco also had a greater advantage Over All Other Staples in That It Could Be Produced in Larger Quantities Per Acre. This Was Important Considering the Labor Required To Clear the Trees and Prepare One Acre for Cultivation. It Was Soon Discovered That the Amount of Tobacco Produced by One Man's Labor Was Worth About Six Times the Amount of Wheat That One Man Could Grow and Harvest. Moreover, Tobacco Could Be Shipped More Economically Than Any Other Crop; Thus the Monetary Return Upon a Cargo Was Greater Than for Any Other Crop That Could Be Produced in the Colony.