Category: Horticulture Highlight

Horticulture Highlight: Common Privet, Ligustrum vulgare

June 4, 2019

To be of use

The people I love best

jump into work head first

without dallying in the shadows

They seem to become natives of that element

and swim off with sure strokes almost out of sight….

            -Marge Piercy

If we were to transpose Piercy’s above sentiment to plants used for hedging, many such lists might include evergreens of yew, boxwood, arborvitae, or holly. A greater number of deciduous choices for hedging could include lilac, forsythia, rose, viburnum, spiraea, azalea, and privet among many others.

We reach’d a meadow slanting to the North;

Down which a well-worn pathway courted us

To one green wicket in a privet hedge…

            -Alfred, Lord Tennyson

Common privet, Ligustrum vulgare are native to Europe and northern Africa. These are many branched, quick-growing shrubs capable of reaching 12 to 15-feet-high, with equally wide spread. The 1-to-2 ½-inch long, dark green, deciduous, simple leaves are placed opposite each other on the stems. In the sixteenth and seventeenth centuries, hedge mazes in large European gardens often were from clipped privet, yew or boxwood. Contemporary gardens still use privet for elaborate and simple hedges, as well as for creative topiary.

Introduced to our country by early settlers during colonial times, common privet eventually escaped from cultivation, becoming naturalized within certain areas of our native flora. This was documented by noted Swedish botanist/explorer Peter Kalm (1716-1779), an early student of and plant collector for Carl Linnaeus (1700-1778), the “father of modern taxonomy.” In his 1770 classic, Travels in North America, Kalm recorded for September 21, 1747, while in New Jersey, “The common privet, or Ligustrum vulgare, grows among the bushes in thickets and woods. But I cannot determine whether it belongs to the indigenous plants or to those which the English have introduced, the fruits of which the birds may have dispersed everywhere.”          

Several generations later visionary founder of Mount Auburn, Jacob Bigelow (1787-1879), physician and botanist, also documented this privet’s naturalized occurrence in his Florula Bostoniensis. A collection of Plants of Boston and its Vicinity, 1840 Third Edition Enlarged, “Leaves lanceolate, acute: panicle crowded. An ornamental shrub with smooth, opposite, spear-shaped leaves, thickening at the ends of the branches. Remarkable in summer for its panicles of small white flowers, and in autumn for its conical bunches of black berries. – frequent in woods and near fences, particularly in Roxbury.”

For those who might suggest that there are more privet hedges in this country than are needed, we end with notable garden writer Allen Lacy (1935-2015) from his 1984, Home Ground: A Gardener’s Miscellany, “…No garden visitor has ever bothered to praise my privet, but its gifts are not to be despised. I have given it no attention at all. I have neither fertilized it nor treated it to some of my precious compost nor watered it except incidentally…But it has thrived…In June it blooms for two weeks, with hundreds of creamy spikes made up of tiny flowers that sweeten the air…The bees love it, and some of its nectar may have found its way into the honey made by a neighbor who keeps bees…” We note here that everyone who has pruned or sheared their privet before the middle of June has already removed the flower buds. It is probable many hedge owners have never witnessed their flowers due to spring pruning and shaping.

Still

in a way

nobody sees a flower

really

it is so small

we haven’t the time

and to see takes time

like to have a friend takes

time

-Georgia O’Keefe

Lacy continues, “…Now its tangled branches have grown into a small thicket where robins nest each year in the spring and sparrows and finches perch in winter…The privet has become the token wild place in my garden, something that links it with the rhythms of the larger order of nature. This fall, like every fall, the abundant blue-black fruits of my privet will feed some of the birds that live year-round in the neighborhood and some of the other birds that gather briefly here before resuming their annual migration southward. Left to itself, with no intention or planning on my part, the common privet turns out to have uncommon quality.”

On a future visit to Mount Auburn look for some of our common and other privets on Fountain Avenue, Willow Avenue, Yarrow Path, Indian Ridge Path, Bluebell Path, Pilgrim Path, Spelman Road, Garden Avenue and Spruce Avenue among other locations.

Like a well-kept lawn a hedge means a well-considered garden.

-Ernest Henry Wilson

Horticultural Highlight: Trillium, wake-robin

April 30, 2019

Let us forget the sorrows: they are there

always, but Spring too seldom there;

Once in a life-time only; oh seize hold!

Sweet in the telling once, but not re-told.

In Nature’s cycle blessed once a year,

not long enough to savour, but more dear

for all the anguish of its brevity…

            -Vita Sackville-West

Any hypothetical definition of spring is subject to countless interpretations, frequently entwined with preferred blossoms. Locally, for some it may be magnolias on Commonwealth Avenue, cherries, serviceberries, dogwoods, redbuds, and/or crabapples at Mount Auburn. But for John Burroughs (1837-1921), American naturalist, he famously put it in print as the Trillium erectum, Wake-robin, red trillium, stinking Benjamin. His half-century literary conservationist career commenced in 1871 with Wake-Robin. His own page one therein, clearly defined spring for him, “…and when I have found the wake-robin in bloom I know the season is fairly inaugurated. With me this flower is associated, not merely with the awakening of Robin, for he has been awake for some weeks, but with the universal awakening and rehabilitation of nature.”

Usually not found by the drive-through spring adherents, these are aesthetic gifts to woodland path aficionados who may perchance be satisfied by a memorable encounter of even a single plant in blossom. Native to the eastern United States and Canada its purple/maroon flowers have three lance-shaped, prominently veined, petals. These perennial flowers are on a short stem (pedicel) above a whorl of three attractive, ovate, green leaves. These nectar-less flowers emit an odor which attracts flies and beetles as pollinators. The variant degrees of fetidness clearly are the source of the less complimentary colloquial name,stinking Benjamin. This allows use here of Alfred, Lord Tennyson’s (1809-1892) quatrain;

What is it? A learned man

Could give it a clumsy name,

Let him name it who can,

The beauty would be the same.

The genus Trillium comprises almost fifty species, primarily native to North America, but with ten species native to Asia. One distinct characteristic of this genus is myrmecochory, the dispersal of seeds by ants. The etymology is from the Greek for ant (myrmex) and dispersal (kore). When Trillium flowers have been successfully fertilized they will eventually produce a 1-inch to 1 1/2-inch, red, fruit capsule within which are numerous1/8-inch seeds. Attached to these seeds are elaiosomes, an appendage rich in nutrients, lipids and/or oleic acids. Ants take these seeds back to their nests to eat or feed their larvae the elaiosomes. The seeds then are discarded, outside or inside of the ant nest. This insect-plant interaction is not unique to trilliums, over 11,000 species of plants benefit from myrmecochory.

Other trillium species to look for include Trillium grandiflorum, big white trillium, which as the name suggests have three white petals. Also, the Trillium undulatum, painted trillium, which have white petals with a distinct red v-shaped marking near the base of each petal. On a future visit to Mount Auburn, look for trilliums at Dell Path, Sumac Path, Buttercup Path and at Spruce Knoll.

I have touched the trillium,

Pale flower of the land,

Coral, anemone,

And not your hand…

            -Helen Dudley

Horticulture Highlight: American elm, Ulmus americana

April 2, 2019

Look, where the bluebird on the bough

Breaks into rapture even now!

He sings, tip-top, the tossing elm

As tho he would a world o’erwhelm.

Indifferent to the void he rides

Upon the wind’s eternal tides…

            -Edwin Markham

 “Don’t cry for me America. I never left you,” scattered locations within Mount Auburn seem to speak to us anthropomorphically. If not with these exact enunciated words, the continuing presence of the oft described canopies of American elms prove these much beloved arboreal sentinels never reached the comparable nadir of our American chestnuts. Nonetheless scores of millions of American elms have died over the last eight decades due to Dutch elm disease (DED).

Yet each April, we continue to count on one reliable phenological sign of New England’s spring, the American elm flowers, collectively tinting winter’s former stark canopies a light, purplish/red color. Weeks before other spring ornamental notables such as forsythia, cherries, magnolias, dogwoods, etc. and well before producing leaves, these flowers are commonly overlooked.Maya Angelou has stated,“Everything in the universe has a rhythm, everything dances.” Hence, after winds as well as early insects have danced through these flowers, cross-pollination fertilizes ovules which develop into elm seeds. These ½-inch, rounded samaras (winged, light-weight seeds) mature in May and can be blown considerable distances from the parent trees.       

Along about then, the middle of May,

I say to myself: “any day…”

And I guess up there in the tall elm trees

The leaves say something like “Listen, breeze:

It’s no good whispering stuff; just blow!

There’s a skyful of seed here set to go.”

And the breeze perks up

And the seeds fly loose-…

            –David McCord

Thomas J. Campanella has authored, Republic of Shade: New England and the American Elm, the definitive overview of this once popular shade tree dominating streets in towns and cities across the country, even designated the state tree of both Massachusetts and North Dakota. Then in the 1930’s, a vascular wilt disease (DED) was accidentally introduced to the U. S. likely on logs imported from Europe for use as veneer.

Great Elm on Boston Common 1810

DED is “Dutch” (actually Asian) because early researchers identifying the fungus were Dutch. DED was a problem in Europe 20 years before coming to our country. Causal organism was initially determined to be the fungus Ophiostoma ulmi (formerly Ceratocystis ulmi) with later an additional more aggressive Ophiostoma novo-ulmi. Compounding and exponentially exacerbating the pathogen virulence were European bark beetles. Transporting fungal spores from infected trees, they bored into the outer bark of elms, making tunnels (called galleries), mating and leaving their eggs under the bark.

Societal reaction to DED, slow at first, ramped eventually into literal overkill. Rachel Carson’s 1962 classic Silent Spring, recounts then contemporary efforts to control these bark beetles using DDT. “Spraying for [DED] began in a small way…soon it became evident that something was wrong…graveyard for most of the robins…at first…suspected some disease of the nervous system, but soon it became evident…robins were really dying of insecticidal poisoning…exhibited well-known symptoms…not so much by direct contact…indirectly by eating earthworms.” She reported on further published research, “killing directly not only the target…bark beetle, but other insects, including pollinating species…the poison forms a tenacious film over the leaves and bark. Rains do not wash it away. In the autumn the leaves fall to the ground…begin…becoming one with the soil…aided by…earthworms…also swallow the insecticide…concentrating in their bodies…become biological magnifiers of the poison…” Finally, “…even as the elm program is only one of the multitudinous spray programs that cover our land with poisons.”  So DED which many communities had mobilized to eradicate unanticipatedly expanded Carson’s grass-roots audience, hence influence, in contrast to assurances of the insecticide people that their sprays were “harmless to birds.” 

…Give me spots on my apples

But leave me the birds and the bees

Please…

            Joni Mitchell

After more than half-a century of research with numerous cultivar selections, no American elm has proven totally resistant to DED. Some however, are tolerant and recover after infection. While American elms will never regain their former prominence, their American tragic saga also provided urban forestry with the lesson to forever avoid the danger of monoculture plantings, as was often common, sometimes near ubiquitous, with American elms. This has led some advocates to consider as a guideline, a 10-20-30 goal. Plant no more than 10% of any one species, plant no more than 20% of any one genera, plant no more than 30% of any one family. The true goal being to ensure genetic diversity within all urban tree canopies.  

On a future visit to Mount Auburn look for some of our grandest mature straight species of American elms on Asclepias Path, Pond Road and Bluebell Path. Other fine examples are found on Arethusa Path, Bigelow Avenue, Harebell Path and Garden Avenue among other locations.

We also have cultivars of ‘Princeton’ on Fir Avenue, Heath Path, Honeysuckle Path, and cultivars of ‘Liberty’ on Fir Avenue, Field Road and Ailanthus Path.

The lovers disappeared into the wood.

I sat among the boughs of the fallen elm

That strewed an angle of the fallow…

            -Edward Thomas

‘Jelena’ Witch Hazel, Hamamelis xintermedia ‘Jelena’

March 4, 2019

My garden will never make me famous

I’m a horticultural ignoramus

I can’t tell a string bean from a soybean

Or even a girl bean from a boy bean

            -Ogden Nash

Questions of bean gender aside, there are occasional, horticultural, true-love stories within our ongoing pastime of “who does your garden grow?” Prime example this time is our late-winter, blooming beauty, ‘Jelena’ Witch Hazel, Hamamelis xintermedia ‘Jelena’ (pronounced Ya-lay-na). This love story commenced in what is today the Kalmthout Arboretum, outside of Antwerp, Belgium, in the mid-1950’s. A century earlier the site began as a plant nursery, passing through two different lengthy ownerships before World War I and the ensuing economic collapse finally closed the business. In 1952 Robert de Belder (1921-1995) and his brother Georges bought the then overgrown, weed covered land/estate. In a raison d’etre echo to Mount Auburn’s and Longwood Gardens’ beginnings, the de Belders, local diamond traders, bought the site to preserve the mature and even rare trees from a proposed housing development.

On a separate life path, heading towards convergence, we introduce Jelena Kovacic (1925-2003), born in what is now Croatia, with a 1951 agronomy degree from the University of Zagreb. With a rare travel permit abroad, this botanist/horticulturist was in 1953/54 studying nurseries and horticultural sites in Denmark, Germany, the Netherlands and ultimately Belgium. Hearing about mature, rare Stewartias along with other ancient trees brought her to the de Belder’s new work-in-progress. A romance quickly developed with Robert, and these plant aficionados were married within three months.

Jelena joined the de Belder brothers, working to restore, replant, re-design and enlarge the long fallow property using a naturalistic style. The extensive plant diversity on the property included thickets with hybrids of witch hazels from the earlier nurseries. One attractive unnamed selection, shown at the Royal Horticultural Society in London, in 1954, was very popular. Robert named this Hamamelis xintermedia ‘Jelena’ in honor of his new wife.

Hamamelis, a small genus with but four (five) species worldwide, produce spider-shaped yellow or orange flowers, each with four, one-half-inch-long, narrow, strap-shaped petals. The two Asian species and their hybrids (crosses of Chinese and Japanese witch hazel) curiously produce their flowers during February and March. ‘Jelena’ in bloom, at first glance has a warm coppery-orange color. Look closer at the flowers to often see petals with reddish bases, orange centers and yellow tips.

Our ‘Jelena’ Witch Hazels on Snowdrop Path, Buckthorn Path and Sparrow Path have shimmered in the otherwise sparse winter landscape after each of the modest February snowfalls we have had so far. The tiny petals protectively curl up during extreme cold and more serious snowstorms, which allows the flowers to last four to seven weeks. ‘Jelena’ additionally will provide attractive red-orange autumn colored leaves.

The de Belders achieved notoriety for breeding Hamamelis cultivars and another winning selection was ‘Diane’, a striking red-flowered cultivar. Hamamelis xintermedia ‘Diane’ was named to honor Jelena and Robert’s daughter. A fine specimen of ‘Diane’ may be found on the southern end of Indian Ridge Path. Both Hamamelis xintermedia ‘Jelena’ and Hamamelis xintermedia ‘Diane’ have received the Royal Horticultural Society’s Award of Garden Merit.

Look for these winter beauties along with other witch hazels as the calendar turns to March.

Let us whir with the golden spoke-wheels

Of the sun.

For tomorrow Winter drops into the waste-basket,

And the calendar calls it March.

                                Amy Lowell