8 TROPICAL AGRICULTURE 



remain strictly herbs in cold climates become shrubs or small 

 trees in the Tropics. The Lantana, which is cultivated as a 

 more or less delicate greenhouse plant in cold climates, be- 

 comes a shrub varying in height from 4 to 15 feet and shows 

 an aggressiveness which makes it one of the very worst of 

 the weed pests. Cotton, which is cultivated strictly as an 

 annual in the cotton belt of the mainland, grows as a perennial 

 in the Tropics and will live and bear for 25 to 40 years, 

 although the best yields are obtained by cutting it back after 

 each crop and treating it practically as an annual. The pigeon 

 pea, which is a useful leguminous cover crop will, if left to itself, 

 become practically a small tree attaining a diameter of eight 

 inches or more. The formation of annual rings in trees is, as 

 is well known, due to the difference in rapidity of growth dur- 

 ing the height of the growing season and the fall season just 

 before growth ceases. Since no such seasons prevail in the 

 Tropics there are no definite annual rings in forest trees. 



Most trees in the Tropics are evergreen, shedding their 

 leaves the year round a few at a time. A few trees, however, 

 shed their leaves all at one time. The Ceara rubber tree and 

 kapok are conspicuous examples of this sort. Notwithstand- 

 ing the absence of temperature seasons in the Tropics, plants 

 nevertheless have seasons of growth and periods of rest. 

 There are, therefore, best times to plant in the Tropics as in 

 cold climates. The reason for recommending particular sea- 

 sons for planting is usually based on the prospects of rain- 

 fall and relatively cool weather. A number of plants thrive 

 best in their early stages if planted at the beginning of the 

 winter season. This is perhaps nearly always true for Irish 

 potatoes and corn, which in Hawaii, at any rate, make a much 

 better growth if planted in November or December than if 

 planted in April. Even this recommendation, however, must 

 be limited strictly to sea level, for at high elevations, particu- 

 larly above 4,000 feet, the best season for planting these crops 

 is in March or April. Many tropical plants, as is well known, 



