FLORA OF HAWAIIAN ISLANDS — HITCHCOCK. 451 



32,000 feet. Geologically Kauai is the oldest island and Hawaii the 

 youngest. On Kauai are found deep and rugged canyons the result 

 of age-long erosion. On Hawaii vast stretches of lava are as fresh 

 as if the material had barely had time to cool ; and several Hows have 

 broken forth within the last century. There are innumerable small 

 craters dotted over the main mountain mass. There is a great 

 variety in the kinds of lava. Some of the cones are made up of cin- 

 ders, a soft material that yields to the foot like sand. Others are 

 made up of hard lava, of which two main divisions are recognized, 

 aa and pahoehoc, Hawaiian terms meaning rough and smooth. The 

 former is exceedingly rough and broken and presents great difficulties 

 to the traveler who attempts to walk over its surface. In the course 

 of time the lava disintegrates sufficiently to allow vegetation to 

 obtain a foothold. The advent of plants is hastened by moisture, 

 the lava becoming covered with vegetation much sooner in the regions 

 of heavy rainfall than upon the arid slopes. 



It will be impossible to give an ecological survey of the islands but 

 it may be of interest to present a brief account of the flora and its rela- 

 tion to environment as it impresses a visiting botanist. 



The most striking botanical feature that greets the traveler on his 

 arrival at Honolulu is the display of ornamental plants, including 

 flowering trees, shrubs, vines, and plants grown for the beauty of 

 their foliage or the stateliness of their habit, practically all of which 

 are of foreign origin. 



There is a great variety of palms, including such pinnate-leaved 

 species as the date, the coconut, and greatest favorite of all, the royal, 

 and many fan palms and a few fishtail palms. The stately royal 

 palm with its smooth columnar trunk is a familiar tree in parks and 

 private grounds. 



Among the street trees there are the pink shower {Cassia nodosa) 

 with large racemes of beautiful pink and white flowers, the golden 

 shower (Cassia -fistula) with yellow flowers and woody, smooth, 

 straight, cylindric pods 15 inches long, both with large compound 

 leaves, and the flame tree (Delonix regia) with great masses of 

 scarlet flowers on the otherwise naked branches, the leaves being 

 deciduous. The monkey-pod or rain tree (Sainanea saman), a 

 large, round-topped or umbrella-shaped tree with an immense spread 

 of branches, is common in parks. 



Among the shrubs the most common is the hibiscus, of which there 

 are scores of varieties, involving several species (especially Hibiscus 

 rosa-sinensu) . These are commonly used for hedges and produce a 

 continuing crop of large, bell-shaped flowers, varying through shades 

 of white, pink, and scarlet. Clambering over a wall around the 

 grounds of Punahou College is a fine growth of night-blooming 



