The fragrance of spring…in winter

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Pendant inflorescences of Edgeworthia chrysantha

Edgeworthia chrysantha, the paperbush, seems to be making the transition from rare collectors’ item to a garden staple that can regularly be found in garden centers.  That’s all to the good, because it is a wonderful plant for piedmont gardens.  It is one of the four best shrubs to grow for winter fragrance–the others being Osmanthus fragrans (tea olive), Lonicera fragrantissima (winter honeysuckle), and Chimonanthus praecox (wintersweet)–and for architectural interest, it beats those other three species hollow.

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The buds open around the outside edge of the inflorescence first.

Edgeworthia forms a perfect dome of thick, flexible branches that are covered with large green leaves in summer. The leaves drop after the first freeze, around the time that the fuzzy flower buds begin to swell, so by late December the bare branches appear to be tipped by silvery Christmas ornaments.  The flowers open from mid February to mid March in central North Carolina and fill the garden with their fragrance.  Currently both Edgeworthia and Lonicera fragrantissima are blooming in my garden.  The Edgeworthia fragrance seems sweeter, and the Lonicera more lemony, but both are wonderful.  If we don’t have a hard freeze in the next ten days they should be joined by the apricot fragrance of Osmanthus fragrans.  My Chimonanthus is still too small to bloom, but in a few years February should smell amazing.

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A few days after the flowers open, their yellow petal tips fade to white, so an older inflorescence has yellow flowers at the center and white ones around the rim.

Edgeworthia seems to grow reasonably well in dry shade, but my best specimen grows where it receives rainwater channeled from the end of the driveway and is exposed to direct sun until mid afternoon.

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A small specimen growing in dry soil at the edge of the woods.
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My larger plant growing in constantly damp soil at the southwest corner of the house.
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The same plant in March 2011

Some websites suggest that Edgeworthia buds can be destroyed by temperatures in the low teens (Fahrenheit), but my plants of the common yellow-flowered variety have tolerated low single-digits with no damage to either buds or branch tips.  The orange-flowered form does seem to be more cold sensitive.  A small specimen that I planted was frozen to the ground several years in a row and failed to come back last spring.

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The common name, paperbush, apparently comes from its use as a source of fiber for Chinese and Japanese paper, although I can’t imagine how anyone could bear to grind up an Edgeworthia for anything so mundane as paper pulp.

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Florist azalea

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Last year, at Easter, my mother-in-law gave us a small potted azalea.  This type of azalea, commonly called a florist azalea or greenhouse azalea, was bred from non-hardy species like Rhododendron simsii for cultivation in in cool greenhouses.  They are commonly available in bloom from florists, garden centers and sometimes even supermarkets.  Some varieties may be marginally hardy in the NC piedmont, especially during mild winters like this one, but they are not as well suited to our gardens as the Kurume and Satsuki hybrids, or even the Southern Indicas which were also derived from R. simsii and related species.

This plant had no tag, and since I have no idea how hardy it might be, I decided not to risk it in the ground.  After it finished blooming, I put it outside in shade and kept the pot well watered through the summer.  As the weather cooled off in autumn, I moved it into brighter light and, eventually full sun.  I left it out until the first hard freeze was forecast, and when I brought it into the house, I put it close to a cool window.  It has rewarded me with these bright, semi-double flowers on a dark, cold, rainy winter day.

Clusia orthoneura, or The Plant That Ate the Greenhouse

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Clusia orthoneura flower

Half the fun of trading or giving away plant cuttings and divisions is seeing what other people can do with the same plants that I grow.  For the past ten years, I have been growing Clusia orthoneura, a strange epiphytic shrub from South America.  My plant resides in a 14″ terracotta bulb pan and is a semi-bonsai.  Every year, I put it outside for the summer, where its branches sprout aerial roots that reach the ground and dig in by the end of the summer.  Each autumn, I cut back those roots and much of the new foliage, so it will fit back into my greenhouse.  As a result, it remains almost the same size from year to year.

About five years ago, I rooted a small cutting and gave it to John Stanton, owner of the Orchid Trail nursery in Morrisville, NC.  John put the cutting in an 8″ diameter pot, and sat it on one of his greenhouse benches.  In the large commercial greenhouse, it wasn’t moved every year, and roots that grew down through the bench weren’t disturbed.  Also, John is an exceptionally good grower.

Earlier this week I stopped by the Orchid Trail in search of a particular slipper orchid species, and John showed me his Clusia.

The plant rises about six feet above the greenhouse bench and is equally wide.

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Under the greenhouse bench, the roots resemble those of a mangrove or a strangler fig.

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The pot is still visible, but most of the plant’s bulk completely bypasses it.  At this point, the pot could be cut away without bothering the plant at all.

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It’s almost unrecognizable as the same species as the stunted little thing in my greenhouse.

Sea myrtle

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Baccharis halimifolia in Durham County today.

Sea myrtle (Baccharis halimifolia) is one of the most striking native shrubs in the NC piedmont at this time of year.  Its fuzzy white seed heads are a common sight beside lakes, in unmown fields, and along roads, where its tolerance for salt is a definite advantage.  B. halimifolia is a member of the Asteraceae, the daisy family, although the family resemblance is difficult to see at first glance.  It’s a woody shrub, instead of a forb, and its inflorescences lack the colorful ray flowers that give the showier members of the family their horticultural value.  However, the white plumes attached to the seeds make the plant look as though it is covered with snow and more than make up for the lack of color.

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I’m surprised that sea myrtle isn’t used more often as a garden shrub for seasonal interest.   Though I have previously criticized the groundskeepers on the campus where I work, I have to admit they have done a good job incorporating some volunteer B. halimifolia into the landscape.  By removing the lower branches, they have exposed the twisted trunks and turned the plants into very interesting specimens.

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The only defects of B. halimifolia from a horticultural point of view seem to be its brittle wood and its production of huge quantities of airborne seeds.  Many horticulturally valuable shrubs are also brittle (e.g. my Hypericum frondosum, which snapped under snow this winter), so that doesn’t seem to be a fatal flaw.  More problematic is its tendency to become weedy.  It is apparently invasive in southern Europe and Australia.  Perhaps it would be best to grow it only in its native range.

San Diego (Six on Saturday #37, November 10, 2018)

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The Botanical Building in Balboa Park

This week, I traveled to San Diego, California for a scientific conference.  It was my first trip to San Diego–my first trip to anywhere in California, actually–so it was exciting to see a new part of the country.  Even the flower beds around my hotel and the convention center were full of new and interesting things.

The meeting didn’t leave much time for sightseeing, but I managed to slip away one morning and take a bus up to Balboa Park, which houses the San Diego Zoo and a variety of gardens.  I considered just wandering around the free areas of the park but eventually decided that I couldn’t miss the world famous zoo.  That turned out to be the correct choice.  In addition to being an amazing collection of endangered species (the zoo is famous for its captive breeding successes), the grounds are also a very fine botanical garden.  The weather was cool, so the animals were active, and there were hardly any visitors.  I had a good long visit with the pandas (red and giant), koalas, Tasmanian devils, komodo dragon, giant tortoises, okapis, elephants, jaguars, and many other animals, but I took more pictures of the plants.

Today being Saturday, here are six things that caught my eye in San Diego–garden related, of course.

1.  Flowering trees.

November is clearly not the best time of year for blooming trees, but nevertheless, I saw some beautiful tropical and subtropical flowers.

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Ceiba speciosa (silk floss tree) in Balboa Park
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Ceiba speciosa flower
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Spathodea campanulata (African tulip tree) in Balboa Park
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Bauhinia x blakeana (Hong Kong orchid tree) at the San Diego Zoo

2. Bird of Paradise flowers

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Roadside Strelitzia reginae

Strelitzia reginae (bird of paradise) and Strelitzia nicolai (white bird of paradise) were growing (and blooming) all over town.  S. reginae is my wife’s favorite flower, so when we were first married I tried growing some from seed.  After fifteen years, I managed to get a only single flower from an enormous clump that took up a lot of real estate in the greenhouse, so I gave up.  Clearly, flowering is not a problem when they are grown outside in San Diego.

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Strelitzia nicolae on the patio of the convention center

3.  The Botanical Building

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The Botanical Building is a Balboa Park landmark that was originally built for the 1915-1916 Panama-California Exposition.  Before seeing it, I had assumed it was some sort of greenhouse or conservatory, but there is no glass involved.  Instead, the Botanical Building is a giant lathe house, built of wooden strips that provide the perfect amount of shade and wind protection for palms, tree ferns, and other tropical/subtropical understory plants.

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Inside the Botanical Building
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Deppea splendens flowering in the Botanical Building.  Oh, how I wish this species would survive a North Carolina summer
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An enormous Ficus sycomorus growing behind the Botanical House.  A photo can’t do justice to the scale of its massive buttress roots.  According to the Gospel of Luke, Zacchaeus the tax collector climbed one of these trees so that he could see Jesus.

4.  Australian plants

Callistemon ‘Woodlanders Hardy’ and one or two eucalyptus are the only Australian plants I know of that can be grown in North Carolina, and even those are marginal outside of the coastal plain.  The climate of southern California is more similar to parts of Australia, so I wasn’t surprised to see a wider variety of plants from Down Under.

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Anigozanthos (Kangaroo paw) in a flower bed at the convention center.  I wonder if one of these could be grown in a pot in North Carolina, if protected from rain?
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A little grove of Brachychiton rupestris (Queensland bottle trees) at the zoo

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I assume this is Australian, because it was growing in the koala habitat at the zoo.  Australian readers, help me out. Is this some sort of Grevillea?  It was growing as a tall shrub, or small tree. [Update:  This appears to be Alloxylon flammeum.  Thanks to Jim Stephens for the suggested identification.]
5. African and Malagasy plants

The zoo has a really impressive collection of succulents from Madagascar and southern Africa.

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Alluadia procera (Madagascar) outside the Elephant Care Center
Cyphostemma
Cyphostemma juttae (southern Africa)
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Pachypodium lamerei and Moringa drouhardii (bottle tree, smooth trunk on left), both from Madagascar
Euphorbia spectabilis
Euphorbia spectabilis (Tanzania)
Uncarina
Uncarina sp. (Madagascar)

6. Hawaiian plants

I suppose the climate of Hawaii, particularly on the drier leeward side of the islands, must be not entirely unlike that of coastal San Diego County.

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Brighamia insignis (Ōlulu, Cabbage-on-a-stick) growing among other Hawaiian plants at the zoo.  Despite the whimsical common name, this is a member of the Campanulaceae, not a cabbage relative.
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Pritchardia hillebrandii (loulu lelo palm) in the Botanical Building

For more Six on Saturday, click over to The Propagator, where you will find his Six and links to other participants.