hort.purdue.edu/newcrop/duke_en...y/Macadamia.html

Macadamia integrifolia: Trees up to 20 m tall, with spread of 13 m; leaves opposite in seedings, later in whorls of 3, pale green or bronze when young, 10–30 cm long, margins with few or no spines, petioles about 1.3 cm long; flowers creamy white, apetalous, borne in groups of 3 or 4 along a long axis in racemes, much like grapes; fruit consisting of a fleshy green husk enclosing a spherical seed; nuts round or nearly so, surface smooth or nearly so, 1.3–2.5 cm in diameter; shell tough, fibrous, difficult to crack; kernel white, of uniform quality, shrinking only slightly after harvesting. Fl. June through to March, some strains almost ever-bearing, flowering while fruiting. Macadamia tetraphylla: Trees up to 20 m tall, with spread of 13 m; leaves opposite in seedlings, commonly in 4's rarely in 3's or 5's, purple or reddish when young, margins serrate with many spines, up to 50 cm long, sessile or on very short petioles; flowers pink, in large racemes; fruit consisting of a fleshy green husk enclosing one seed; nuts usually elliptical or spindle-shaped, surface pebbled; kernel grayish; variable in quality and shrinking some after harvest. Fl. between August and October, producing one main crop. Between these two distinct types are numerous intermediate forms varying in spininess of leaves, color of flower, size of nut and thickness of shell.


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