Written by davethetreecenters • April 11 The Pine Trees of America #1
PART 1, IDENTIFICATION
Pine Trees are everywhere, in city and country, and their distinctive long needles make them a tree that is almost as widely recognized as maple. As garden trees, pines have a lot to offer, especially in these times of reduced watering. Most grow well in dry, sandy soils, enjoying sun yet throwing a much lighter shadow than most shade trees. So you can often garden beneath them better than beneath a maple.
This may surprise some people, whose experience with pine trees involves the dense, deep-shade Austrian Pine – a great tree for screening, but not so good for planting underneath. Most other pines cast a much lighter shade, and are much more friendly to plants beneath them. If you are looking for native pines for your garden, or already have pines in it, then this group of blogs will be of great interest.
Since pines like acidic soil, and make the soil around them acidic in time, the plants you grow underneath them should love acidic soil too – but hey, that means rhododendrons, azaleas, mountain laurel, ferns, and most shade-perennials like Hosta and astilbe, so that’s a pretty good selection.
Because so many of our garden plants were brought here from Europe by settlers – and by nurserymen who already knew how to grow the plants they grew at home – many people are surprised to learn that the most common pines seen in cities and gardens are not American, but European species. As well, some Japanese pines are popular, but few of our own pines are seen in most gardens.
The most common pines in cities and most gardens are Austrian Pine (Pinus nigra), which we have already mentioned, Scots Pine (Pinus sylvestris), and Mugo Pine (Pinus mugo), that lovely dwarf pine that forms dense mounds of foliage for shrub beds and rocky places. I wouldn’t suggest for a moment not planting these lovely and valuable trees, but they are not native to North America. So, with the interest in native plants that is such a big movement in gardening today, let’s take a look at the most important of our native pine trees.
We will start off in this blog by looking at how you identify pine trees – we all see trees we can’t put a name to – beside perhaps ‘pine tree’. Let’s take that a little further and open our eyes to the magic of plants and the world around us. Then we look at 5-needle pines in the second blog, 3-needle pines in the third one, and 2-needle pines to finish our tour.
Identify Your Pines
You might think all pines are the same, but they aren’t. A common request is for identification of an unknown pine tree, and that isn’t as hard as you might think. At least in natural areas. In gardens the range of possibilities is wider, so we will stick here mostly to American native pines, but include a few of the most common exotic species native to other countries be often grown in gardens and parks.
There are two key things you need to try and identify a pine – needles and cones. Bark is also useful.
The needles part is easy, so let’s start there.
The Arrangement of Pine Needles.
At first glance you might think that pine needles are just a bunch on the end of a branch, but look more closely. See how the needles are actually arranged in little bundles? These are called fascicles, and they are the first thing to look at. Some pines – called hard pines – have a permanent papery sheath around the base of the bundle, giving it a stiff look. Others, the White Pine (Pinus strobus) is a good example, lose that papery sheath once the needles mature, giving them a more open, pendulous look – so they are called soft pines. Notice if your pine is a hard pine or a soft pine.
Secondly, each bundle of needles contains the same number – count them. Is it 2, 3 or 5? Those are the only choices. So, for example, if you find a pine with 2 needles in each fascicle, there is a good chance that it is Jack Pine or Virginia Pine, if it isn’t growing in a garden. If you see a conifer tree, and it doesn’t have needles in bundles like this, then it isn’t a pine tree.
Pines with 5 needles in the bundle – the Soft Pines
- Eastern White Pine P. strobus
- Japanese White Pine P. parviflora (exotic species)
- Limber Pine P. flexilis
- Sugar Pine P. lambertiana
- Western White Pine P. monticola
Pines with 3 needles in the bundle
- Lace-bark Pine P. bungeana (exotic species)
- Loblolly Pine P. taeda
- Longleaf Pine P. palustris
- Monterey Pine P. radiata
- Pitch Pine P. rigida
- Ponderosa Pine P. ponderosa
Pines with 2 or 3 needles in the bundle (variable)
- Slash Pine P. elliottii
- Shortleaf Pine P. echinata
Pines with 2 needles in the bundle
- Austrian Pine P. nigra (exotic species)
- Jack Pine P. banksiana
- Japanese Black Pine P. thunbergi (exotic species)
- Japanese Red Pine P. densiflora (exotic species)
- Mugo Mountain Pine P. mugo (exotic species)
- Red Pine P. resinosa
- Scotch Pine P. sylvestris (exotic species)
- Shortleaf Pine P. echinata
- Virginia Pine P. virginiana
As well as the number in each bundle, notice the length of the needle, and the white row or rows along one side. These are stomata – openings for air in the otherwise water-proof needle. All these things are useful for identification.
The second feature to use for identification are cones. This can be harder, as a young tree may not have any, and on a old tree they can be many feet in the air –binoculars can help. Look around, though, because cones can often be lying on the ground underneath a tree – try to be sure they didn’t drop from a different pine nearby.
- Cones vary greatly in length. Some are almost round or egg-shaped. Others are long and slender, or large.
- Some cones can have hard, woody scales, others have softer, more papery scales. Young cones will be tight, while old ones – most of those on the ground – will have their scales spread open, which releases the seeds inside.
- Cones also vary in color as they mature, which can also be helpful.
In the next blog I am going to take a look at some of the different native pines that are most common, and that are also the most likely to be growing in gardens or parks, as well as of course growing wild somewhere in this huge country.
If you like the idea of being able to identify pines, and want to take this further, this link is to an excellent key created by Arnold Arboretum in the 1950s. Very little has changed in the naming of pines since then. It covers all but 4 native species and most of the exotics you might find – 38 species in all. This is a simple key, which is the way most botanists identify plants. You will see that the features are all easy to see and find.
A key works by giving choices. You start with the first question – #1, which is about needle number. It is repeated several times through the key, starting with 5-needle pines. If yours has 3 needles, go down to the #1 group on page 4. Then go to the #2 question beneath it. Each question leads to another question or to the name of a species. Take a look and you will get the idea. More work than looking at pictures, but a lot more accurate. Some practice with real examples will make the use of it clearer. Have fun!