passion flower (Passiflora edulis)

Passion flowers, a prelude to passion fruit, have an astonishing look, unmatched by any other floral display. They have an extraterrestrial aspect and have been likened to alien spacecraft spinning in the night sky. Alternatively, they could take their place alongside certain luminescent sea creatures.
From the standpoint of horticultural expertise, growing passion vines and having them develop flower buds and flowers is no big deal, but fruit production is not to be taken for granted. The most common edible species, Passiflora edulis, may require manual pollination because many varieties are self-sterile to some degree.
Self-fertility and, by contrast, self-sterility are terms that refer to the ability or inability of a plant to pollinate itself. It is actually to the advantage of plants – if not to gardeners – to be somewhat, if not completely, self-sterile. That quality typically means increased receptivity to the pollen of other plants (clones, varieties or cultivars) of the same species so that genetic diversification in the next generation is assured.
A self-fertile plant will have a limited gene pool since its pollen mostly comes from the same mother plant (itself) and few genes from outside pollen sources will be mixed in with its own genes when pollination, embryo and seed formation take place. A self-fertile plant may, therefore, be less capable of tolerating sudden environmental stress – from drought, disease or insect pests, for example – than a self-sterile plant, which draws from a larger gene pool, including genes that impart resistance to a spectrum of environmental stressors.
The flavicarpa variety of passion vine (Passiflora edulis flavicarpa) produces yellow fruit that may reach the size of a grapefruit with accompanying acidity. Purple-skinned varieties of passion fruit, although smaller – between the size of a plum and a lemon – are sweeter than the larger yellow fruit.
Before purchasing a passion fruit variety make sure it is reliably self-fruitful. Even it it is, you may have to wait up to five years before seeing a significant crop. To increase pollination and fruit set, take a small paintbrush and transfer pollen grains or dust (forming at the ends of five radial anthers) to sticky stigmas (at the tips of three central pistils).
If passion flowers have no equal, likewise leaves of the Bodhi tree (Ficus religiosa) are incomparable.
When I look at Bodhi tree foliage, I see stingrays, those potentially deadly ocean denizens. Yet it was this same tree under which Siddhartha Gautama (later known as Buddha) supposedly sat for many days and eventually found the enlightenment he sought.
There is a Bodhi tree in India that is more than 2,300 years old and, although its foliage is sparse, it perseveres.
My experience with this tree instructs that it should never be pruned. When you cut it, it grows out in unpredictable and haphazard ways. The only hope of achieving a relatively symmetrical dome is to simply let it grow.
It suckers profusely and, like certain other species of ficus trees, its roots are a threat to surrounding pavement, creating fissures and pushing up sidewalk slabs of concrete.
You would think that golden rain tree (Koelreuteria paniculata) would be a desirable garden specimen for several reasons. First, upon maturity, it reaches only 40 feet in height, making it ideal for a backyard where shade is sought but not at the price of total darkness because the tree you chose never stops growing. Second, it has an attractive umbrella-shaped canopy. Third, it produces huge panicles of golden flowers in late summer and fall. Fourth, it can grow in a lawn.
Yet, it is seldom seen in Los Angeles. Being deciduous, golden rain tree does endure a period of leaflessness and this could be a factor in its lack of use. Seeds also germinate quite easily so that you will be constantly removing rain tree seedlings from your surrounding beds.
Flame tree (Koelreuteria bipinnata), a golden rain tree cousin with crimson flower clusters, is more frequently encountered.
Larry Wible, from Los Angeles, sent a picture of a plant I had seen pop up sporadically over the years and always wanted to know more about. I uploaded the picture to the plant and tree identification forum at http://davesgarden.com and learned that this mystery plant is none other than sorghum (Sorghum bicolor).
Sorghum, a member of the grass family, is an important cereal crop, the staff of life in tropical and arid zones throughout the world, particularly in its native Africa. Because it lacks gluten, it has become popular among those who are gluten intolerant. All parts of a sorghum plant may be used for livestock.
Tip of the week
German or cape ivy (Delairea odorata), from South Africa, makes a wonderful houseplant. A member of the daisy family, it has succulent leaves resembling ivy, and thrives in a sunny room. It is easy to start from a cutting and will thrive in a variety of soils and watering regimes. It emits a pleasant fragrance when pruned. However, never plant cape ivy outdoors. It has become a noxious weed in California and has been known to smother a tree after encircling its trunk and growing up through its branches. When you pull it out of the ground, cape ivy will rapidly regrow if the tiniest piece of root is left behind.