Aquidneck Island Originals – The origin stories of five local plants

'Amy Cotta' produced by the thousands at Portsmouth Nursery. Photo Credit - Steve Cotta. 

Ever since I began my journey in horticulture, the origin stories of plant cultivars have always been extremely fascinating to me. These captivating tales always remind me of the eternal connection between plants and people, shaping our history up to the present day. Humans have been propagating superior plants for thousands of years, selecting for certain qualities that give them added value over the typical wild type or species. These qualities may include disease resistance, increased fruit production, dwarf growth habit, and anything else that may benefit the cultivator. In modern times, plant discoveries and introductions are often thanks to the hard work and keen eyes of professional growers and amateur enthusiasts. Often times, luck is involved, either by a chance encounter with a plant wherever it may grow, or through mother nature’s ability to spontaneously produce something extraordinary right before our very eyes. Sometimes we can make our own luck through hard work, with the planting of thousands, even millions of seeds, hoping that just one of the resulting plants separates itself from the others.We can increase our chances through controlled crosses and hybridization, picking good parents to produce even better children. It is no surprise that growers are always in pursuit of exceptional plants. After all, eye-catching (good selling) and horticulturally valuable plants are vital for the survival of nurseries and landscapers, and key to the success of public gardens and arboreta.

Aquidneck Island has a rich horticultural history, and several valuable plants that appear in gardens near and far were “born” right here on the biggest island in Narragansett Bay. In this article, I will discuss the cultural history and current landscape status of the more common Aquidneck Island plant introductions. It is a story of people, their life’s work, their love of plants, and the legacy they leave in our gardens and landscapes.

Before I start diving into the plant stories, I would like to explain an interesting botanical phenomenon that is relevant to the majority of the plants featured in this article. A branch sport is a genetic mutation, spontaneously occurring or induced, appearing as differentiated growth on an individual plant. The mutation could be very similar in morphological characteristics to the plant it appears on, or vastly different. A specific type of branch sport is referred to as a witch’s broom, where growth is very dense, producing many shoots with shortened internodes from a single location on a branch. Vegetative propagation of the mutated plant material results in a propagule that will retain these characteristics, but reversion back to the normal form is possible and sometimes common. Not all reversions are complete, and sometimes these reversions may result in unique characteristics as well.

A Hinoki Falsecypress (Chamaecyparis obtusa 'Gracilis') reverting in Island Cemetery Newport.

Newport Blue Boxwood

Buxus sempervirens ‘Newport Blue’

Boulevard Nurseries, Middletown RI

Sheared 'Newport Blue' at The Blue Garden in Newport

‘Newport Blue’ boxwood originated in 1941 at Boulevard Nurseries in Middletown, Rhode Island. According to John Kempenaar Jr, it was a seedling raised at the nursery, likely the result of a cross with unknown parentage. The original plant was selected and propagated by Esau Kempenaar, who is John Jr.’s great grandfather. Esau immigrated to the United States in the late 1800s from Holland, first working under Vanceslaus A. Vanicek at Rhode Island Nurseries. In 1910, Esau stepped away to start his own nursery with Frederick Christensen down in Newport. Based on the characteristics of ‘Newport Blue’, it appears as though the selection may be a cross between common boxwood (Buxus sempervirens) and Asiatic or little leaf boxwood (B. microphylla). This would offer some explanation as to the compact habit, foliage characteristics, and boxwood blight resistance of the now widely grown seedling.

The shape of unpruned 'Newport Blue' at a private garden in Newport

The new growth of B. sempervirens 'Newport Blue'. Photo Credit - Waverly Farm Web Page

Carrying a great name that perfectly suits the plant, ‘Newport Blue’ has captured hearts for almost 80 years with its appealing blue toned leaf color, finely textured evergreen foliage, and tidy, compact habit. In early spring, the tender new growth of the plant produces a handsome, soft silvery blue color. As the growth hardens off in the summer, the leaves become a glossy dark green. Foliage holds up well in the winter, with little to no leaf burn. If left untouched, which is the best way to grow it, ‘Newport Blue’ will mature to 5 feet tall by 5 or 6 feet wide, perhaps larger with old plants. Growth is slow but steady, equating to about 4-6 inches a year. For best performance, site in full sun, ideally in a protected location, and plant in acidic, well-drained loamy soil. Propagation is done by hardwood cuttings collected in the fall, which root easily.

The summer foliage of 'Newport Blue'

The popularity of boxwood has dwindled in recent years, with the emergence of boxwood blight (Calonectria pseudonaviculata), a fungus that causes brown lesions and significant dieback of the leaves and stems. Severe infection often leads to plant fatality .The European or common boxwood (B. sempervirens) cultivars, which ‘Newport Blue’ is considered, tend to be more susceptible to boxwood blight than the Asian species (B. microphylla, B. sinica, B. s. var. insularis) and cultivars. ‘Newport Blue’ is reported as resistant to boxwood blight, but not immune. Despite this, the plant still has a large presence in commerce, and is offered by several local nurseries, and as far afield as Oregon.

Rhode Island Red Japanese Maple

Acer palmatum var. atropurpureum ‘Rhode Island Red’ syn. ‘Bloodgood Compacta’

Rhode Island Nurseries, Middletown RI

The newly emerging foliage of 'Rhode Island Red' at a garden in Portsmouth

The outstanding and very popular ‘Rhode Island Red’ Japanese maple, sometimes referred to as ‘Bloodgood Compacta’ Japanese maple, deservedly earns its place in gardens throughout the United States. Speaking with and hearing from Acer palmatum enthusiasts, the plant is held in very high regard within the Japanese maple growers community. This is quite the achievement, as it is difficult to compete for recognition against the overwhelming mass of cultivars available. It is exciting to think that a first-class Japanese maple cultivar, widely available in commerce, was discovered at a local nursery here on Aquidneck Island. It should be noted that Japanese maple varieties have been selected for centuries, and cultivars have emerged from all corners of the globe.

The brilliant color of 'Rhode Island Red' in the summer

The discovery of ‘Rhode Island Red’ occurred by accident. In the mid 1980s, Tom Vanicek, a propagator at Rhode Island Nurseries at the time, was collecting propagation material from a block of ‘Bloodgood’ Japanese Maples (Acer palmatum ‘Bloodgood’) that were set to be sold. ‘Bloodgood’ is a very common red leaf (var. atropurpureum) form that matures to be 30 feet tall and wide. As luck would have it, one of the cuttings taken, a scion to be grafted, was a piece of a branch sport that went undetected during the collection process. It wasn’t until 6 or7 years later, when the plant was a third the size of its companion maples in the liner, that Rhode Island Nurseries realized they had propagated a branch mutation by happenstance. The plant was then dug up, propagated via further grafting, and named ‘Bloodgood Compacta’.

The excitement was palpable around the nursery, as they loved the plant. However, it didn’t sell all that well, possibly because the name didn’t resonate with the gardening and growing public. One day, a sales representative from Iseli Nursery out in Boring, Oregon was visiting the nursery and happened to notice ‘Bloodgood Compacta’ stock. Enamored by the qualities of the plant, the salesman asks for propagation material to be sent back to the west coast. Rhode Island Nurseries agreed, and soon, the dwarf maple was being grown across the United States. Sometime later, on a nursery tour through Iseli’s famous stock planting, guests were charmed by the plant, eager to know its identity and if they could purchase one. Known for their many awesome plant introductions and marketing acumen, Iseli reached out to Rhode Island Nurseries owner Bruce Vanicek, proposing to rename the plant ‘Rhode Island Red’, like the famous chicken breed. Bruce quickly agreed, and from there, sales of freshly minted ‘Rhode Island Red’ took off, giving some deserved exposure to Rhode Island Nurseries, and the rest is history.

So what is it about ‘Rhode Island Red’ that gets people so excited, like those touring at Iseli Nursery that day? The leaves emerge in the beginning of May with brilliant, dark red color. The red coloration holds up well through the heat of the summer, darkening and bronzing a little bit in the summer sun, before brightening to brilliant scarlet red towards the end of October. The plant stays squat, spreading horizontally with short internodes and readily dividing, densely branched growth. An old plant in Middletown has achieved a height of 15 feet tall and wide. It is usually grafted onto a 12-inch standard (stem) to lift the growth off the ground, allowing it to form a better shape. This small tree performs best with some partial shade but will thrive in both sunny and shady sites. Moist loamy soils are preferred, but adaptability is in this plant’s nature. Very wet or dry soils could be problematic.

Close up of the leaf of A. palmatum 'Rhode Island Red'

'Rhode Island Red' summer foliage color

A grafted standard, a foot high, of A. palmatum 'Rhode Island Red'. Notice the graft union just below the branching

Amy Cotta Rhododendron

Rhododendron ‘Amy Cotta’ PJM Group

Portsmouth Nursery, Portsmouth RI

One of the original 'Amy Cotta' plants in the garden of Steve Cotta. Photo Credit - Steve Cotta

One day in 1982, walking through a field of 3,000 PJM rhododendrons (Rhododendron ‘PJM’), Portsmouth Nursery Owner Steve Cotta witnessed something interesting. Spawning out of a branch on a single rhododendron, was a clump of twigs with small, dark green leaves and short internodes, standing out like a sore thumb against the mass of PJM clones. Intrigued by the foliage and growth habit qualities of this spontaneous occurrence, Steve was able to get about 20 cuttings from this mutation, rooting most of them. In time, however, many of these propagules reverted to the characteristics of typical PJM rhododendron to varying degrees. With a great deal of patience and perseverance, Steve continued to propagate the plants that retained some of the initial sport characteristics, and after a few years, he had a handful of attractive reversion proof plants with beautiful foliage and densely compact habits.

The PJM rhododendron has a local history of its own, as this plant is one of many rhododendron hybrids that were developed at Weston Nurseries in Hopkinton, Massachusetts. The original PJM rhododendron is a cross between the Atlantic coast native Piedmont rhododendron (R. minus var. minus), and the deciduous Dahurian rhododendron (R. dauricum var. sempervirens). Hundreds of named cold hardy rhododendrons and azaleas have emerged from the extensive breeding work at Weston since 1943. The name PJM is an acronym honoring Peter James Mezitt, great nursery man and plant propagator, who was the mastermind behind the creation of these hardy Rhododendrons.

The flowers and foliage of  'Amy Cotta'. Photo Credit - Steve Cotta

Wayne Mezitt, current chairman of Weston Nurseries, would make a trip down from Hopkinton, MA to Portsmouth nursery to visit the newly minted shrubs. He would confirm the plant was unlike anything that had been bred at Weston, and gave Steve permission to name the plant. Wayne would also comment that he too had seen this mutation on ‘PJM’ as well but had never done anything with it. Not long after, at an International Plant Propagator’s Society Meeting, Steve would be encouraged by plantsman Dr. Micheal Dirr to put a patent on the rhododendron. Of course, the plant needed a good name before it was introduced into commerce. Unable to choose between his wife and daughters, Steve decided to name his new rhododendron after his grandmother, Almorinda ‘Amy’ Cotta. Amy had at one point donated the land to her son Henry Cotta (Steve’s Father) to start Portsmouth Nursery. These days, roughly 3,000 ‘Amy Cotta’ rhododendrons are sold annually from the nursery of origin, and one of the original plants grows happily in Steve’s home garden.

A very cold hardy flowering shrub, ‘Amy Cotta’ is a slow growing rhododendron, evergreen with almost black-green summer foliage that is retained even in the harshest of winters. It is grown with absolute success from Maine to California to Minnesota. The ruffled, lavender pink flowers emerge in mid-April when color is at a premium. The bloom color and timing is very similar to the standard PJM type, perhaps a little darker if you view the shrubs side by side. If the weather is cool and gentle, the flowers can remain showy for over two weeks. A gardener could expect the plant to creep its way to about 5 or 6 feet tall, developing a densely rounded habit.

Boulevard falsecypress

Chamaecyparis pisifera ‘Boulevard’ Syn. ‘Cyano-viridis’

Boulevard Nurseries, Middletown RI

'Boulevard' planted as a screen

Historically, it may be true that Boulevard falsecypress is the most widely known of all the Aquidneck Island plant introductions. It’s also true that authentic ‘Boulevard’ scarcely exists in today’s nursery trade, showing up in only a few recent nursery catalogs. In 2024 Rhode Island, this intriguing conifer with soft, bluish green, needle-like foliage is still represented in older landscapes by venerable, weathered specimens. Several old plants can be tracked down throughout Aquidneck Island, often appearing when least expected. Closely allied, and perhaps superior plants that originated as branch sports or as select seedlings of ‘Boulevard’ are still available for purchase. These plants can be found by searching names such as ‘Devon Cream’, ‘Baby Blue Ice’, or ‘Curly Tops’; there are certainly others as well.

‘Boulevard’ Falsecypress, like most of the other plants featured here, had quite the spontaneous beginning. It was discovered as a branch sport on Moss falsecypress (Chamaecyparis pisifera ‘Squarrosa’) in 1934, spotted by the well-trained eye of Esau Kempenaar of Boulevard Nurseries. This sport, or perhaps more appropriately termed “Witches Broom”, would have appeared as a tuft of dense foliage with longer needles and deeper blue color (more glaucous). It is not known exactly where this mutation occurred, but ‘Squarrosa’ would have been extant on a few of the old estates in Newport. Cuttings were taken, rooted, exchanged, and planted. The plant was originally named ‘K and C’, which stood for Kempenaar and Christensen. These would be the last names of Esau and Frederick, respectively, business partners and owners of the nursery at the time. However, as the conifer made its way farther and farther away from Aquidneck Island, the name ‘Squarrosa Cyano-viridis’ seemed to attach itself to the plant; this name appears in old literature and nursery listings occasionally. According to John Kempenaar Jr., the name of the plant changed to ‘Boulevard’ after Christensen’s death.

The awl shaped, needle-like foliage of 'Boulevard'

A side by side comparison of C. pisifera 'Squarrosa' and C. pisifera 'Boulevard'. Photo Credit - oregonstate.edu

Opening its doors in Newport in the year 1910, Boulevard Nurseries was originally located down between Kay St and Bliss Ave, and along Eustis Ave on roughly 30 acres of land. Kempsen Street, which intersects with Eustis, is named in honor ofthe two original owners, conjoining the two last names. In the early years (1920s and 30s), the nursery specialized in roses, evergreens, rhododendrons and azaleas. According to John Kempenaar Jr., Esau would partner with a local Newport machinist to create a machine that produced tar paper pots, a production method that would later be refined and developed further, eventually being used to create the widely popular, compostable pots known as Jiffypot®. The nursery would move to a new location in Middletown off Valley Rd in the 1930s, expanding to around 600 acres at its largest size. The storied 1938 hurricane would apparently prove to be beneficial to the business, as nearly all the nursery stock, mostly large trees, were bought up off the yard in a single day following the disaster. Esau would pass away in 1972, with the nursery being operated at that time by his 3 sons, Fred, Charles Sr., and Robert. In 1995, the nursery closed temporarily, opening again in 2001 at its current location along East Main Road. Today, the business is in its fourth generation of being family owned and operated.

Maturing to around 25 feet tall or larger over many years, ‘Boulevard’ takes on a narrow pyramidal shape. Growth is slow, but not painstakingly so if planted in fertile soil and given full sun. Plenty of plant people will tell you the biggest downfall of ‘Boulevard’ is that, with age, the plant’s habit becomes more open, exposing brown needles that cling to the branches. With confidence and a little skill, proper pruning can improve the shape and density, but consistency is key. Interestingly, despite the acicular foliage being juvenile growth, ‘Boulevard’ will sometimes produce seed cones. It should be stated that in present times, ‘Boulevard’ falsecypress exists as somewhat of an enigma. In the nursery trade, it’s highly probable the ‘Boulevard’ and ‘Squarrosa’ are confused regularly. Newer permutations of ‘Boulevard’ may also be mistaken for the original, with these plants often being improvements, with denser growth habits and more attractive foliage. Reversions are likely to take place as well, which only adds to the pile of suspect plants that fall somewhere in the complex.

'Boulevard' Falsecypress at Rogers High School in Newport

Hoogendoorn Japanese Holly

Ilex crenata ‘Hoogendoorn ’ syn. ‘Hoogendoorn Compacta’;

‘Compacta’

Hoogendoorn Nurseries, Middletown RI

The compact shape of I. crenata 'Hoogendoorn' in a Newport Garden

According to Dick Hoogendoorn, the original plant was discovered by his father, Case Hoogendoorn, growing somewhere in Newport County in the 1930s or 40s. Cuttings were collected, and the plant was given the name Ilex crenata ‘Compacta’. Considering the many old I. crenata specimens in Newport, it might be theorized that, like Rhode Island Red Japanese maple, propagation material was collected from a branch sport inadvertently. We may never know this for certain. Knowing a hardy broadleaf ever green for hedging had lots of value, the plant went into production at the nursery. It should be noted that Case Hoogendoorn was a pioneer in the nursery industry, awarded the International Plant Propagator’s Society Eastern Region Award of Merit in 1970, for his significant contributions to the field of plant propagation and production. Fast forward 30 or so years from the plant’s initial propagation, when stock of ‘Compacta’ was shipped down to a nursery in Virginia, and not long after that, plant material found its way into the hands of prominent nursery man Tom Dodd Jr. in Semmes, Alabama. ‘Compacta’ was not protected with a plant patent, so nurseries were able to freely propagate and sell it. Dodd is credited with renaming the plant ‘Hoogendorn Compacta’, paying homage to its origin. Dodd Jr. was involved with IPPS, so it is likely he knew Case personally, and of Hoogendoorn Nurseries. Due to its individuality, landscape value, and to avoid confusion with similar plants, the name was then shortened to ‘Hoogendoorn’ in early 2000s.

Today, ‘Hoogendoorn’ Japanese holly is an extremely common hedging and foundation plant throughout the United States. It stands out with the best of the best Japanese holly cultivars, like ‘Steeds’, ‘Helleri’, and ‘Convexa’. When asked how big the plant will get if left untouched, Dick Hoogendoorn responded with a laugh and said, “I don’t know”. One might assume a 60 or 70 year old plant left to its own devices might be able to achieve sizes far greater than what is written in books. What is certain is the plant will remain densely branched without pruning, carrying lustrous evergreen foliage, with individual leaves roughly an inch in length. ‘Hoogendoorn’ is a male holly, so it will not produce any fruit, but will pollinate other female I. crenata types. Best in full sun, ‘Hoogendoorn’ will tolerate some shade. Deer are fans of this plant, but they typically just give the plant a shearing with their browse.

A row of I. crenata 'Hoogendoorn'

The leaves of I. crenata 'Hoogendoorn'

By Joe Verstandig — Living Collections Manager

November 2024

A special thank you to Bruce Vanicek, Dick Hoogendoorn, Ronn St. Jean, Steve Cotta, John Kempanaar Jr., Brian Maynard, and Elaine Conway.

References:

Dirr, M A. 2008. Manual of Woody Landscape Plants. 6th Ed. Stipes, Champaign Il

Dirr, M A. 1977. Manual of woody Landscape Plants. 2nd Ed. Stipes, Champaign Il

Cotta, Steven. 1998 New Plant Forum Eastern Region. Combined Proceedings International Plant Propagators’ Society, Volume 27

Breen, Patrick. 2024 Landscape Plants. Oregon State University College ofAgricultural Sciences Landscape.https://landscapeplants.oregonstate.edu