On the corner of Riverside Drive and Hazeltine Avenue in Sherman Oaks, two gold medallion trees are in full bloom. If you are wondering how these trees got their name, just take a look at their spherical flower clusters which, from a distance, have the appearance of circular gold medallions, a kind of botanical bling.As budgets for tree pruning are pinched, gold medallion trees (Cassia leptophylla) are planted more frequently because of their moderate size. Mature gold medallion trees reach a height of only twenty-five feet. At the same time, their canopy spreads out to thirty feet and thus, in the shade below, you can place a picnic bench for having lunch al fresco on a summer day.Gold medallion flowers, after they fade, are followed by very long chocolate brown pods, which impart considerable ornamental interest of their own. These pods may grow up to two feet in length. Kids enjoy shaking them like castanets since the seeds inside make noise as they rattle around. Attractive dark, fissured bark is showcased when leaves drop off, if only briefly, during the winter.Although native to Brazil and considered a tropical species, gold medallion trees can survive temperatures in the mid 20’s and are highly drought tolerant, too. Germinating gold medallion seeds is easy. Pick up fallen pods, split them open, and remove seeds, placing them in a cup or bowl. Boil water and pour it over the seeds. By volume, there should be a ratio of 10 parts water to 1 part seeds. Let seeds sit in water for 24 hours and plant.This same procedure may be used for germinating seeds from most leguminous trees. Leguminous trees include carob, coral trees (Erythrina species), acacias, orchid trees (Bauhinia species), black locust (Robinia species), honey locust (Gleditsia triacanthos), and mimosa (Albizia julibrissin). Leguminous trees with extremely hard seed coats, such as mesquite (Prosopis species), may require a dunk in sulfuric acid in order to germinate. While most of these trees are characterized by pinnate foliage, where two rows of narrow leaflets line up opposite each other on the stem, linear and compartmentalized seedpods are common to them all.An advantage of planting leguminous trees is that they manufacture their own nitrogen with the help of symbiotic bacteria that inhabit nodules in their roots. Thus, leguminous trees are suitable for planting in nitrogen poor and desert soil.There is a new tree on the block that also blooms in July and is worth mentioning here. I refer to Black Diamond crape myrtle trees. Black Diamond trees are so-named on account of their deep burgundy, virtually black foliage. These trees grow to a height of 12 feet and, from what I have seen, are as suitable for hedges as they are for containers and as stand alone subjects or accents. Black Diamond crape myrtles are also mildew resistant and, in the manner of crape myrtles generally, seem to flower most following a dry winter. They are available in several shades of red as well as in pink, blush, white, and purple.Crape myrtles of every description, all of which are deciduous or leafless during winter, are best pruned at winter’s end. The reason for this is that flowers are produced on shoots that being growing in the spring. If you prune earlier, new and tender growth could begin prematurely, during a warm spell in February, for example, that could be damaged later on by a sudden freeze.Ted Howard, whose Flower’d by Howard gardens have long been familiar to Valley residents, has adopted fertigation to provide a constant mineral feed to his plants. Fertigation involves integration of a feeding tank into an irrigation system so that each time water is applied, fertilizer is applied as well. Howard adds bio-stimulants to his fertilizer mix, too.Howard says that 5 months ago he was applying 30 gallons of water per day to a 125 square foot garden of his own, located near the corner of Roscoe Boulevard and Coldwater Canyon. Prior to planting , he amended his soil with 10 cubic feet of ordinary planter mix and water-retaining crystals that acquire a gel-like consistency and sponge-like quality upon hydration. Since May, thanks primarily to fertigation, he has been able to cut his garden water use by half. Keep in mind that water in Los Angeles costs less than a penny per gallon so that while he was spending around $2 per week to water his garden 5 months ago, he is spending around $1 per week today. It should be noted that Howard utilizes lengths of drip tubing, set 6 inches apart, to irrigate his garden. Otherwise, his water usage would be significantly greater.Tip of the Week: Up on the south side of Mulholland Drive, just east of Laurel Canyon Boulevard, there is a magnificent Australian flametree reaching skyward among a copse of humdrum arboreal fare. Native to the east coast of Australia, Australian flame trees exhibit considerable cold tolerance and may be even be grown in Acton. In addition to their matchless scarlet, bell-shaped flowers, foliage is softly lobed and a sparkling emerald green in color.