Spring is upon us now, taking us all for a wild ride of temperature swings, rain and wind, and hopefully, no more snow, though blizzards still scream west and north.
The occasional farm field is covered with Lamium purpureum, the “devouring purple monster” or purple dead nettle weed. Coltsfoot is sunny yellow on stream banks and highway banks. But let us turn to horticulture: to magnolias and their blossoms arriving now, to Japanese kerria soon to come, to the extreme yet restrained horticulture of bonsai, and to the ancient grace of ginkgo.
• Magnolias. Magnolias are among the most spectacular tree flowers in the Ohio landscape palette, and the early bloomers really give the season a boost. Our first are star magnolias. While taking my Sustainable Landscape Maintenance class to New York City last weekend, star magnolias were just starting to bloom at the Brooklyn Botanic Gardens and across the city, a touch ahead of us here in Northeast Ohio. Our time arrived Wednesday with the first bloom in Wooster.
These blooms are highly predictable, not by calendar date, but by growing degree-days, heat units that have accumulated for the year. For star magnolia, 83 growing degree-days means first bloom, and we reached that in Wooster on Wednesday. The date is different for plants in different areas of Northeast Ohio, in more sun, and so on, but the number of growing degree-days required is reliable. Check out the tally for your ZIP code at www.oardc.ohio-state.edu/gdd.
The star-like white petals of star magnolia are followed by the purples of saucer magnolia at 133 degree-days. A day with a high of 60 degrees will provide about five growing degree-days, and one of 70 means 10 growing degree-days, and so on with a somewhat more complicated formula reported on the website, but the move forward is inevitable with the warming days (the growing degree-day clock never moves backward).
In between star and saucer magnolias are many hybrids, including the Loebner hybrids of star magnolia and Magnolia kobus, and the ‘Little Girl’ hybrids (‘Anne, ‘Betty’, ‘Jane’ and others) that are crosses of star magnolia and Magnolia liliflora. Later this spring, we will see the yellow magnolias, the sweetbay magnolia and even the southern magnolia, which is surviving farther northward these days.
But those early magnolias are especially lovely and welcome. Longtime observers note another temperature factor that comes into play: in many years, the star and saucer magnolias are nipped by Jack Frost, but as I look at the next two weeks, I do not see much of a threat. This may be one of those years when stars and saucers shall have a long floral life. Do not fail to smell the magnolias.
• Japanese Kerria. One of the most welcome signs of spring is the sight of lemon-yellow, four-petaled forsythia flowers that dot landscapes or with forced branches on the dinner table or windowsill. Yet what if forsythia fails as the season springs forward? Pair your forsythia with Japanese kerria. This shrub is attractive all winter with its green stems, and then, a week or two after forsythia fades, on come the five-petaled bright yellow kerria flowers.
Kerria is in the rose family (Rosaceae) and you can see the blossom’s similarity to the open look of roses and other members of this family, such as apple, strawberry, cherry and plum, all with five petals and loads of pollen-bearing stamens. Forsythia is in the Oleaceae, along with privet, ashes, fringetree and lilacs, all with four petals.
I had not realized that the genus Kerria is named for William Kerr, so should probably be pronounced as “cur-ee-uh,” instead of “care-ee-uh,” though almost everyone goes with the latter. Oddly, this is similar to the pronunciation of Forsythia, which by all rights should be “for-sigh-thee-uh,” since it is named for William Forsyth, rather than the commonly used “for-si-thee-uh.” However these plants and their flowers are spoken, I pronounce that they are lovely and welcome.
• Bonsai. At the Brooklyn Botanic Garden there is a bonsai collection, and for me, it was a reacquaintance with this ancient art that combines Chinese, Vietnamese, Japanese and other East Asian traditions of growing normal-sized woody plants in confined shallow dishes that result in smaller root systems, stems and leaves, all with the shape of the larger plant. I have seen collections at Dawes Arboretum outside Newark, Ohio, at the U.S. Botanic Garden Conservatory in Washington, D.C., and elsewhere, and my sister-in-law Pam grew bonsai plants.
In Brooklyn, I was most amazed by the ancient Rocky Mountain juniper, 500 years old with a craggy trunk and green-blue foliage, a full 2 feet tall and 3 feet wide in its dish after all these centuries. I was most charmed by a Pieris japonica, a Japanese Andromeda. This is a common Ohio landscape plant we have at Secrest Arboretum at normal size, perhaps 4 feet by 4 feet. In fact, we noticed the tiny drooping flower clusters of the Pieris at Secrest before departing for New York City.
Like other members of the heather family, Pieris, as well as blueberries, enkianthus and azaleas, have bell-like flowers. All the plants in this family thrive in well-drained, acid soil, but Pieris is more tolerant of variations. What I noticed on the bonsai Pieris was a lovely nuance, which reflects what Peter Chan, writing in the 1987 book “Bonsai Masterclass” (as noted in Wikipedia), says: "The purposes of bonsai are primarily contemplation for the viewer, and the pleasant exercise of effort and ingenuity for the grower."
The nuance was something I never noticed in looking at Pieris for many decades. Bonsai brought it out. The graceful sepals are the least talked about of what botanists speak of as the four floral envelopes. There are petals, collectively known as the corolla. There are the pollen-bearing stamens. There are the female flower parts, the pistils comprised of the stigma, style and ovaries.
The sepals, collectively known as the calyx, are often green and leaf-like and subtend the petals in many plants. On Pieris, all my life I have missed the sepals, lovely little five-pointed stars. Check it out.
• Ginkgo. Ginkgoes are unusual plants. Like pines, spruces and firs, they are gymnosperms, seed plants but not truly flowering plants. Gymnosperms do not have their seeds enclosed in fruits, but rather seeds are “naked,” on scales or on cones. As for the males, cones were just coming out on ginkgoes at the Brooklyn Botanic Garden last week, in Northeast Ohio this week, and are attractive up close.
The tiny emerging leaves will soon follow, miniature versions of the wide fan-shaped leaves to come. These are harvested for a wide array of herbal medicines, including Ginkgo biloba memory aid products. Ginkgoes originated in China, and similar leaves are found in fossils over 270 million years old.
The female reproductive structures, fleshy arils known by some as “golden apricots,” are widely used in Asian cuisine. These fleshy arils have several unfortunate characteristics, however. They contain butyric acid, which smells like vomit. So unless you want to carefully collect female arils of ginkgo for the nuts inside, removing the outer smellacious flesh, avoid buying female ginkgo trees.
To add insult to injury, the flesh also contains urushiol, an alkaloid also found in poison ivy. So, un-careful, un-gloved collectors risk the allergic reaction. But the male cones, the emerging leaves, the urban-healthy tree (again, buy the males) and the fall color all are worth planting ginkgo trees.
And hear this, the lovelorn poetry of Goethe, using the two-lobed leaves of ginkgo as metaphors:
“This leaf from a tree in the East,
Has been given to my garden.
It reveals a certain secret,
Which pleases me and thoughtful people.
Does it represent One living creature
Which has divided itself?
Or are these Two, which have decided,
That they should be as One?
To reply to such a Question,
I found the right answer:
Do you notice in my songs and verses
That I am One and Two?”
Jim Chatfield is a horticultural educator with Ohio State University Extension. If you have questions about caring for your garden, write to email@example.com or call 330-466-0270. Please include your phone number if you write.