Pinus Envy?

 Size Matters When Growing Conifers

To me, it is a wonder the way a plant that has been grown from rare seed, selected by one individual, and then propagated and distributed around the world is still that same genetic plant, selected maybe 50 or a hundred years before, and passed hand-to-hand from the individual who first held it. Growing dwarf conifers is great fun and price-wise, paying maybe $40.00 for a dwarf conifer seems cheap compared to growing many perennials for $10.00 or $15.00.

In this article I discuss one of the dwarf species and more will follow...

Pinus strobus ‘Merrimack’, the Merrimack Eastern White Pine, is a dwarf conifer growing in a rounded shape to 60 cm high x 80 cm wide. 'Merrimack'-- Sounds like a Gardener's 'Happy Meal!. Cv. 'Merrimack' has soft silvery-grey needles, and its small, squat stature makes it suitable for Japanese gardens and container (instant bonsai) growing (and perfect for bringing inside at Christmas!).

Origins. P. strobus 'Merrimack' was propagated from a seeding grown from a 'witches' broom' on P. strobus, the tallest native tree of Eastern North America, by Al (Alfred) Fordham (1911-2000), who was the head propagator at the Arnold Arboretum in Boston, USA in the 1960s and 1970s (Ref; Ref 2). 

Al Fordham with a Picea abies 'Reflexa' 
at the Arboretum (photo from Bob Fincham)

Al Fordham wrote about the propagation of P. strobus  seedlings from sports affected by 'witches' broom' in 1967 (PDF). In the article, he suggested that the witches' broom symptoms were associated with rust infection, and described the performance of seedlings grown from seed of pine cones collected from witches brooms on several conifer species (Ref 4). It is likely that Cv. 'Merrimack' is a selection from the seedlings referred to in his article. 


According to Plantwise.org, the western gall rust (Endocronartium harknessii) is restricted to North America, and causes galls and witches' broom symptoms (PDF2) on several Pinus spp. including P. strobus. However, many other references do not list Eastern White Pine as a host of this rust, and the genus Endocronartium may become a synonym of Cronartium (Ref 3). P. strobus is however affected by pine blister rust (Cronartium ribicola from Asia, but not present in Australia), which has Ribes spp. as  alternative hosts. So maybe a rust was the cause of the witches' broom symptoms from which Fordham propagated  cv. 'Merrimack'.

Pinus strobus 'Merimack'  newly potted,
 and in my garden in late Autumn 2012

What's in a Name?  Alfred Fordham’s father had been superintendent of R and J Farquhar Company, an important nursery and importer of rare and unusual plants that had been introduced by the botanist, Charles Sargent, and the plant collector, Ernest H Wilson. Al Fordham, the propagator's propagator,  worked at the Aboretum until 1977 but he continued to contribute to plant propagation research until his death in 2000.
 
The name 'Merrimack', along with other Fordham selections of Pinus banksiana, 'Chippewa' and 'Neponset', were chosen in recognition the American Indian heritage in the New England area of the US.  

Merrimac means 'swift water place', and a town of that name on the Merrimack River (below in 1910) in Massachusetts recognises the native American tribe that inhabited the area. 

Merrimac River (in 1910)

'Chippewa' and 'Neponset' are also rivers in Massachusetts named after local Indian tribes, so this may have been a common theme in Fordham's naming. The cultivars flowing like rivers to growers all over the world!

'Chippewa' in their own language means, 'to roast until puckered up'and refers to the puckering in seams of moccasins when held too close or too long toward a fire (Ref 5)


In the Niponset language, their name means 'he walks in his sleep' (Ref 6). A town on the Niponset River, Milton, is home to Baker's Chocolate, the oldest chocolate manufacturer in the USA, founded in 1780!

Milton's Walter Baker Chocolate Factory to the right on the Niponset River.

In addition to several names cultivar selections, Al Fordham, starting in the 1960's created a seed herbarium - with collections of literally hundreds of rare and unusual tree taxa, that the arboretum continues to maintain today (Ref 7) 

Growing Conditions. P.strobus grows best in well-drained soil with cool humid climates, but the natural habitat also includes boggy areas and rocky places. This suggests that cv. Merrimack may also be some what tolerant of similar growing conditions. The white pine also holds its needles well after harvest, making it popular as a Christmas tree.


Uses. White pine needles are also said to contain 5 times the amount of Vitamin C as lemons (Ref 4) when made into a tea (?) and the inner bark was considered to be a famine food by some North American tribes. It was known as "The Tree of Peace" to some native Americans.