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Plant Focus: Sourwood

September 30, 2019 • Leave a Comment

Photo: Steve Nikkila / Perennial Favorites

by Eric Grant

The autumn winds of October bring thoughts of pumpkins, apple cider and hay rides. The season is announced with the anticipation of a kaleidoscopic array of fall colors. These changing hues celebrate the landscape at one of its finest moments. Few trees can herald the autumnal change with the vibrancy of sourwood (Oxydendrum arboreum). Sometimes called the sorrel tree (referring to its leaves), or lily of the valley tree (for its blooms), fall is only one of four outstanding seasons for this little known tree of wonders.

“Spring green” must have been defined by the foliage of this tree. Its soft, but stately outline breaks the winter rest by cloaking itself in the freshest shades of green. Its glossy foliage always seems to shimmer as it progresses through its rainbow range of color. When other flowering trees have finished their brief show, sourwood is about to embark upon a stunning and extended display of fragrant blooms. By mid June, the branches of this tree are generously graced with delicate fronds, which gently hang amidst the now dark green foliage. These creamy white panicles are abundantly tipped with small white “bells” offering an effect not unlike Victorian lace thoughtfully woven throughout the canopy. Sourwood is a tree that refuses to leave its glory with faded flowers. It continues to build its drama beyond the blooms, which last for weeks. Even once the flowers fade, the skeletal lace that held them remains for months, and continues to endow the tree with visual pleasure from the end of spring to beyond the autumn. This is a showy feat upheld by few other trees.

Now comes October. Sourwood is in the midst of act three. The performance is one of color and form, which on its own upstages burning bush, sugar maples, and other outstanding fall color plants. In their presence, however, sourwood only stands to enhance and compliment their beauty. This tree now offers a vibrant display of yellow and purple splashed amidst its predominant color—one of the most brilliant reds I’ve seen on any plant! The intensity of color is richly translucent and always draws remarks of awe. By October’s end, even though it will have dropped its leaves, sourwood does not abandon aesthetic pleasure. As winter winds approach, it again reveals its soft structure and its dark and furrowed bark, a most appealing silhouette against the winter snow. It waits in rest, to begin its cycle again, secure that its series of encores will never disappoint its audience.

Native from the Midwest into the Smoky Mountains, this problem-free tree will mature to 25 feet or so. Given its medium size and a slightly rounded, pyramidal shape, it is easily incorporated into most landscape settings. It enjoys full sun, but tolerates light or dappled shade equally well, and is often found thriving along woodland borders. Sourwood performs well in average to acidic soils, and from loamy peat to sandy beds. While it prefers relatively moist soils, once established, it can even withstand dry seasons. This tree appreciates some shelter, but for the Michigan gardener, is generally less temperamental than dogwoods or magnolias, which are more common flowering trees of comparable size.

Sourwood is a tree of prominence in any season and deserves consideration in the modern landscape. It is rewarding to find a plant with so many attributes that has not been overused. In fact, as one of landscape’s best kept secrets, its novelty offers one of the highest prizes for gardeners—this is a plant your neighbor doesn’t have!

Sourwood

Botanical name: Oxydendrum arboreum (ox-ih-DEN-drum ar-BORE-ee-um)
Plant type: Deciduous tree
Plant size: 25-30 feet tall, 20 feet wide
Growth rate: Slow
Habit: Pyramidal shape, with drooping branches
Hardiness: Zone 5
Flower color: White
Flower size: 1/4 inch long on 4- to 10-inch long clusters
Bloom period: Summer
Leaf color: Green in spring, turning to dark green; red, yellow and purple in the fall
Leaf size: 3-8 inches long, 1-1/2 to 3-1/2 inches wide
Bark: Grayish brown to black
Light: Full sun to partial shade. Flowering and fall color are best in full sun.
Soil: Well-drained, average to acidic, moist soil. Does fairly well in dry soils.
Uses: Specimen tree
Remarks: Native American tree; four-season interest.

Plant Focus: Obedient Plant

September 4, 2019 • Leave a Comment

Physostegia virginiana ‘Pink Bouquet’ (Photo: Jonathon Hofley / Michigan Gardner) — *Physostegia virginiana* ‘Pink Bouquet’ (Photo: Jonathon Hofley / Michigan Gardener)

By George Papadelis

Obedient Plant is a truly versatile plant, with many desirable features that make this North American native an asset in a sunny perennial garden. The flowers somewhat resemble a dragon’s head and thus the common name of “false dragonhead” evolved. These one-inch flowers come in white or shades of pink and are formed in straight rows along a narrow, pointed, spike-like flower head. Although it is a bit deceiving, the common name “obedient plant” developed for another good reason. If pushed to one side, the individual flowers stay in that position for quite a while and are therefore “obedient.” In his book, The Harrowsmith Perennial Garden, Patrick Lima describes it this way: “If you have nothing else to do, you can reposition the individual flowers, which are attached to their stems by the botanical equivalent of a ball-and-socket joint.”

The term “obedient” cannot be confused with the plant’s growth habit, which is, in fact, quite the opposite. If left to do as it wants, this plant produces underground stolons that will make a large clump from a single plant in just one season. This is especially true in well-cultivated, rich soil. Therefore, I recommend planting in poorer soil or be prepared to divide this spreader every year or two in the spring.

Physostegia virginiana ‘Variegata’ (Photo: Eric Hofley / Michigan Gardner) — *Physostegia virginiana* ‘Variegata’ (Photo: Eric Hofley / Michigan Gardener)

Left: Physostegia virginiana (Photo: Stephen Still) Right: Physostegia virginiana ‘Variegata’ (Photo: White Flower Farm/Michael Dodge)

Obedient plant likes full sun and may require staking if planted in part sun or in rich soil. It will begin blooming in August and will continue through the end of September. It has strong, straight stems and long-lasting flowers that make this a popular and beautiful cut flower.

Several different varieties are available. ‘Summer Snow’ is a nice 28-inch tall, white selection, but the most popular color is pink. ‘Pink Bouquet’ is widely used, but grows 3 to 4 feet tall. For a deeper pink on a less floppy, 20-inch tall plant, try ‘Vivid.’ For a wonderful combination of flowers and foliage, use ‘Variegata,’ which has the typical pink blooms but also glowing, white-edged leaves. These stand out in any flower bed and give this variety a much longer season of interest.

If you are willing to curb this plant’s appetite for space, Physostegia may work well for you. As a cut flower or a late-blooming perennial, this plant grows easily. If all else fails, you can always show a fellow gardener why this is called the obedient plant!

Obedient Plant

Botanical name: Physostegia virginiana (figh-so-STEE-jee-a vir-jin-ee-AH-na)
Common name: Obedient plant, false dragonhead
Plant type: Perennial
Plant size: 20 to 42 inches tall
Flower colors: White, rich pink
Flower size: 1 inch long, on spikes above the foliage
Bloom period: August and September
Leaves: Green, narrow, 3 to 5 inches long; also green with white edges
Light: Sun to partial shade
Soil: Grows in most soils; poorer soils will slow rapid spreading
Uses: Cut flowers, wildflower garden, larger naturalized areas
Remarks: Will spread aggressively. If used in the perennial border, plan on lifting and dividing every year or two. May require staking when grown in partial shade or highly fertile soil.

George Papadelis is the owner of Telly’s Greenhouse in Troy and Shelby Township, MI.

Plants can tell time even without a brain

August 20, 2019 • Leave a Comment

Yahoo News:

Anyone who has travelled across multiple time zones and suffered jet lag will understand just how powerful our biological clocks are. In fact, every cell in the human body has its own molecular clock, which is capable of generating a daily rise and fall in the number of many proteins the body produces over a 24-hour cycle. The brain contains a master clock that keeps the rest of the body in sync, using light signals from the eyes to keep in time with environment.

Plants have similar circadian rhythms that help them tell the time of day, preparing plants for photosynthesis prior to dawn, turning on heat-protection mechanisms before the hottest part of the day, and producing nectar when pollinators are most likely to visit. And just like in humans, every cell in the plant appears to have its own clock.

But unlike humans, plants don’t have a brain to keep their clocks synchronised. So how do plants coordinate their cellular rhythms? Our new research shows that all the cells in the plant coordinate partly through something called local self-organisation. This is effectively the plant cells communicating their timing with neighbouring cells, in a similar way to how schools of fish and flocks of birds coordinate their movements by interacting with their neighbours.

Read the rest of the story…

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Sourwood

Obedient Plant