climbing or pink jasmine (Jasminum polyanthum)

You might think of jasmine as a delicate plant for cloistered gardens, where the soft scent of its perfume can be leisurely inhaled as it gently wafts through fresh, untainted air.
Yet, at least three species of jasmine are tough freeway plants that seem to thrive on the fumes of myriad automobiles that pass close by them each day.
Plants that can stand up to such abuse should go to the top of the list when selecting species not only for cloistered, highly manicured gardens, but for gardens where a minimum of tender loving care, because of time or budgetary constraints, is available.
If, in the course of your daily commute, you traverse the 101 Freeway on your journey from the Valley to downtown Los Angeles, look to the south between the Lankershim Boulevard and Barham Boulevard exits.
Draped over a fence running parallel to the freeway, you will see an exquisite blanket of white with pink highlights. This is a horticultural marvel known as Chinese evergreen jasmine, pink jasmine or, for simplicity’s sake, climbing jasmine.
Climbing jasmine (Jasminum polyanthum) has no fear of heights, growing up to 20 feet where it has a tall fence or tree trunk to twist around. I have seen it planted at the base of those sky-high, bean-pole, mop-headed Mexican fan palms (Washingtonia robusta), where it obligingly covers their naked trunks with a layer of deep green, followed at winter’s end by a dense display of white flecked with pink.
With climbing jasmine, it happens that the unopened flower buds are pink while the blossoms of the opened flowers are white. Flowering is primarily at this time of year, but less intense blooming is known to occur at any time.
Climbing jasmine’s strong fragrance is an added bonus.
Plants should be cut back as soon as blooming ends to ensure another heavy crop of flowers the following year. Where plants are not annually pruned, winter flowering varies from one year to the next.
If you take the 118 Freeway east and transition to the 405 Freeway north, you will notice on the right side of the transition ramp a shrubby plant with yellow and white flowers. This is none other than primrose or popcorn jasmine (Jasminum mesnyi), so named because its puffy blossoms resemble the eponymous movie theater snack.
Popcorn jasmine produces arching shoots that eventually hang down, yet it also has a semi-vining growth habit and will clamber up vertically if a trellis is placed close by. Popcorn jasmine flowers are mildly aromatic.
By the way, if you are looking for a plant that smells like popcorn, you will find it in popcorn cassia (Cassia didymobotrya), a large, airy shrub that grows 4 to 6 feet tall. The pinnate foliage of this leguminous plant has the aroma that you seek.
In addition, foot-long flower spikes hold 2-inch yellow flowers that emerge from distinctive black buds throughout the year, but especially in summer and fall.
At the freeway ramp in question, there is also a massive display of royal blue lupine (Lupinus), a California native. If you are enamored of the flowering spires of snapdragons and larkspurs, you will appreciate the large, fat, unblemished inflorescences of lupine.
Once you see lupines in bloom, you will want to grow your own. This is achieved by broadcasting their seeds over fast-draining soil in the fall, waiting for rain, and watching them germinate, develop and flower at this time of year.
After their flowers fade, they will drop seeds that will lead to an even more abundant and brilliant lupine display the following year. Since lupines are legumes and make their own nitrogen in root nodules, no fertilization is necessary.
Due to its minimal water requirement, Italian jasmine (Jasminum humile) was a popular freeway plant at one time, although it is seen only occasionally these days due to its tendency to turn into a mass of terminally green, but otherwise brown, stems unless it is thinned out every now and then.
It, too, has arching shoots, but may be trained to grow up trellises and arbors as well. The bloom time of Italian jasmine coincides with hot summer days. Flowers are yellow and pleasantly scented.
Tip of the week
Two other jasmines, although not seen on freeways, are worthy of either garden or container planting.
Angel wing jasmine slowly grows into a medium-size shrub (Jasminum nitidum) that flowers mellifluously and abundantly from spring to fall. The double flowers of sambac jasmine (Jasminum sambac) `Grand Duke’ are perhaps the largest, with the dimensions of large cotton balls, and are among the most pungently fragrant of any jasmine species.