Many legume trees are notorious for their prolific production of seedpods, which are usually large and in many cases stink when cracked open. Such pods affect both the beauty and sensory perception of the tree, and may be slippery and hazardous on walking surfaces. For example, Samanea (Albizia) saman, which has naturalized in many tropical and subtropical places and is commonly known in Hawaii as monkey pod tree, is a favorite landscape tree in Hawaii for its large canopy, especially in parking lots and parks. Unfortunately, this species produces a large amount of sticky pods that stick to shoes and tires, and can create an objectionable mess, a high volume of green waste and high maintenance of parking lots. The seedpods are heavy to rake and can cause damage to lawn mower blades. Seedless cultivars would have no potential to become invasive and their maintenance cost would be much lower. Seed-bearing ornamental plants can be converted to triploid, non-seed-bearing forms, and thereby eliminate their invasiveness and reduce their maintenance. Triploid plants rarely produce functional gametes, because they do not undergo normal meiosis, and the resulting sterility accounts for the economically valuable seedlessness of triploid bananas, limes, and seedless watermelons. Sterile nursery plants can be used for landscaping virtually without any possibility to become invasive. In a field trial at the University of Hawaii Waimanalo Research Station, it was observed that tetraploid plants of Samanea (Albizia) saman on diploid roots grew similarly to mixoploid and diploid plants on diploid roots. These tetraploid plants were developed by treating the apical meristem of diploid seedlings with 0.1% colchicine for 48h. Therefore, the root system remained diploid, while the above ground portion of the plants were tetraploid. However, tetraploid plants on tetraploid roots, grown from seeds harvested from tetraploid induced plants, were inferior to triploid plants on triploid roots. Triploid plants were almost double in size (67% taller, had 109% wider canopy, and 90% larger DAB, n=8). This is the first time that this phenomenon has been documented in Samanea spp.
