Our History at Home offerings typically sprout from history and architecture. Today, and once every month, we offer a conservation cornucopia from the Conservancy and some friends on trees, gardening, and stormwater management. We hope to help you “Bloom Where You Are Planted.”
Morris Arboretum’s Retired F. Otto Haas Executive Director
The Canadian or eastern hemlock is among the most beautiful of our native conifers. It has a native range stretching from eastern Canada south to the mountains of northern Georgia and Alabama. At its best, it is a long-lived, massive forest tree reaching heights of over 150 feet. Trees in the Smokey Mountains have been documented to be well over 500 years old.
Here in Pennsylvania, Canadian hemlock does not grow quite so large but is widely distributed throughout the state. In northern parts, nearly pure stands of majestic hemlock trees still persist, though here in the southeast, hemlocks are more scattered, mainly on the north slopes of stream valleys, like the Wissahickon. It is also widely cultivated in our landscapes, often to provide screening for windbreaks and privacy. It is highly shade tolerant compared with many other evergreen conifers and grows well among and under deciduous trees. Since 1931, Canadian hemlock has been the official state tree of Pennsylvania.
The bark of Canadian hemlock is rich in tannins. Native Americans used the boiled bark to treat wounds and stop bleeding. Hemlock bark was an important tannin source for the leather industry.
In recent decades, Canadian hemlock has been plagued by an insect, the hemlock wooly adelgid. This sucking insect looks like small, cottony masses on the underside of the needles. This pest is common in the Wissahickon Valley forest as well as in our landscapes, causing thinning of the tree’s crown and often eventual death.
Many notable, healthy, mature Canadian hemlocks are growing in Pastorius Park. Through the efforts of the Friends of Pastorius Park, these trees have been treated regularly to control the wooly adelgid, as well as elongate hemlock scale, another troublesome insect pest. Healthy hemlocks like these in the park are rarely seen today and they demonstrate the lush, delicate beauty for which Canadian hemlock is admired.
In the late 1980s Morris Arboretum staff observed that a rare Chinese Hemlock (Tsuga chinensis) growing in its collection showed resistance to the wooly adelgid. A review of other specimens of Chinese hemlock growing in the region backed this up. Since the 1990s The Morris Arboretum has been a member of an international team (The North American – China Plant Exploration Consortium) collecting and evaluating Chinese hemlock from many parts of its natural range in China. These plants are now maturing and showing great resistance to the wooly adelgid. In 2006 the Morris Arboretum donated young plants of Chinese Hemlock to Pastorius Park, to be planted in memory of Olivia Skye Eble-Schrader. These trees have thrived and are now over 20’ tall. They can be seen growing northeast of the pond on the edge of the woods.
Many compact, slow growing cultivars of Canadian hemlock have been selected and asexually propagated over the years. One of the most dramatic of these is the Weeping Canadian hemlock, (Tsuga canadensis ‘Sargenti’ or ‘Pendula’) It was found in upstate New York as a natural variant in the 1850s and was first propagated in the 1860s. It was first shown publicly in Philadelphia at the Centennial Exposition in Fairmount Park. Two of these trees remain today. Also, two fine weeping specimens grow at the Morris Arboretum – one near the Swan Pond and the other on the edge of the parking lot near Meadowbrook Avenue. The Swan Pond tree, documented on a 1909 map, is well over 100 years old.
In spite of the challenges, Canadian hemlocks continues to be planted, but regular treatment is required to keep them healthy. Chinese hemlock is more reliable but not yet widely available commercially. Resistant hybrids, developed at the US National Arboretum, are also coming along. Research is underway evaluating the use of a beetle that preys on the wooly adelgid. It is hoped that in time, research on many fronts will pay off and Canadian hemlocks will again thrive in the wild as well as in our communities.
Chestnut Hill Conservancy is regularly highlighting special trees in our community, both large and small, as well as common and obscure. In doing so we hope to promote an appreciation of our arbor legacy and foster a culture of stewardship and renewal of this invaluable resource.
Photos by Paul W. Meyer:
Top: Well-tended Canadian Hemlocks screen Pastorius Park from the traffic of West Abington Avenue.
Second: A cluster of Canadian hemlocks provide screening for a home on Willow Grove Avenue.
Third: Hemlock wooly adelgid, a sucking insect, infesting Canadian hemlock growing in the forest along the Wissahickon Creek.
Fourth: Naturally occurring Canadian hemlocks growing on the steep banks of the Wissahickon, near Valley Green.
Fifth: The backdrop for the Pastorius Park Ampitheater stage is formed by a grove of Canadian hemlocks.
Sixth: A grove of the rare, wooly adelgid-resistent Chinese hemlocks was planted in 2008. These trees, donated by the Morris Arboretum, were planted in memory of Olivia Skye Eble-Schrader.
Bottom: Mature weeping Canadian hemlock at the Morris Arboretum, growing near the parking lot along Meadowbrook Avenue.
by Emilie Lapham, Conservancy Board Member, avid gardener, botanical artist, and active participant in several noted local and national garden organizations.
A seed is an embryonic plant enclosed by a protective outer coating. Seeds are an incredible aspect of nature and immensely important to our existence. The beginning of the year is a good time to talk about the start of life in the horticulture world. Seeds offer promise, change, nourishment, beauty, entertainment and excitement. Yes, excitement!
The science of seeds is a huge topic but here is a bit of information before we talk about a project. World’s largest seeds…Lodoicea or coco de mer can grow to 12 inches long, while the smallest seeds are produced by the orchid Gomesa…dust like seeds that blow into the rainforest canopy to find the best conditions to thrive.
Seeds are dispersed in three ways…by wind, water or animals. Just in case you are picturing how animals “garden”, think about squirrels hiding acorns in the ground, but most of the dispersal comes from birds and animals eating in one place and excreting in another.
The winter season keeps us inside more than other times of the year and
this year we will spend much more time at home than usual. Thus, we need projects to engage our attention. Watching a plant germinate and grow can be very rewarding – especially if you can eat what you have grown. Here is a project for everyone to enjoy and it is an easy, sustainable thing to do.
Grow microgreens and cat grass indoors
Seeds Purchase seeds from a garden center or order online. I order from Botanical Interests because this company has a large selection, instructions and supplies. Primex is an excellent local resource. A few of the possibilities for micro- greens are lettuce, broccoli, mustard, kale, beets, cress, radish and peas.
Supplies For containers I recycle take-out containers as mini greenhouses. This might be an opportunity for a take-out night! You want shallow containers with a top, if possible (plastic wrap also works), potting mix or vermiculite, and a spray bottle.
Plant Punch a few drainage holes in the container and if you have a matching one place it below as a tray with a spacer like a bit of gravel. Add a one inch layer of potting mix that has been moistened ( warm water is helpful ). Sprinkle seeds across the surface, pat lightly and cover with a thin layer of mix. Spray if needed and put the lid on or plastic wrap. Place your mini greenhouse in a sunny spot in the house. Grow lights are great too.
Do not let the plants dry out. Check every day to be sure it remains moist but not wet. Mist periodically, if necessary. In a few days there should be activity -germination is exciting. Adjust the cover if it looks too wet but don’t remove until the plants seem sturdy enough. Grow until the plants are about two inches high and in two to four weeks you should be able to harvest and enjoy tiny delicious microgreens! Just clip at the soil line with sharp scissors and enjoy.
Your cats would love for you to grow fresh grass for them also. The procedure is the same. Flora & Jax highly recommend you grow grass for your cats, but I am not sure what the dogs would say about that.
Seeds are so important to life on earth that there is a cold storage seed bank in Norway. More about that in the future. Here is one of my favorite seeds.
All Photos by Emilie Lapham
Introducing our A Gardener’s World webpage, featuring the full gallery of articles and images. Check back each month as we contribute these wonderful features! Click HERE.
Ask the Experts – Going Solar
Virtual Presentation on February 18
February 18, 7pm
Virtual Zoom Presentation
Micah Gold-Markel, founder of Philadelphia-based Solar States, a solar installer and educator, will discuss residential solar electric systems as a way to invest in clean energy and the local community. His frequent collaborator Chris Kurtz of Kurtz Roofing will join the conversation to answer questions about installations on historic houses.
A free, virtual program, Ask the Experts addresses a featured topic by an expert on prevalent issues relating to historic home and landscape care. Ask questions; get solutions! Organized by the Chestnut Hill Conservancy and co-sponsored by the Chestnut Hill Community Association.
Free, registration required. Zoom link and details will be sent to registrants.
Academy of Natural Sciences at Drexel needs your help
to find and control spotted lanternflies
If you’re reading this, you’ve probably already seen swarms of spotted lanternflies in your neighborhood.
The Academy of Natural Sciences and researchers at Drexel’s College of Engineering are working to stop the spread of the spotted lanternfly by developing technology to automatically detect lanternfly eggs.
You can help this project by contributing photos of lanternfly eggs and egg masses!
New egg clusters and an adult spotted lanternfly on garden tool