Garden Word of the Day
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Pine trees, junipers, the mighty redwood are all members of an ancient family, the conifers.
Conifers have been around for 300 million years. They were the dominant plant of the Mesozoic Period, or the Age of Reptiles, and a primary food of many herbivorous dinosaurs.
Adding conifers to a landscape is an excellent way to create year round color. They make excellent anchor plants and they often create food and habitat for wildlife, increasing your garden’s biodiversity.
All conifers are perennial woody plants that get thicker and larger with age. The secondary growth that allows a giant redwood to attain its amazing size all takes place in the cambium layer, just under the bark. Conifers (Pinophyta) are unlike many of our common garden plants, and for several reasons. The most obvious difference is that conifers are gymnosperms, which are cone-bearing seed plants.
Botanically, a cone is called a strobilus. Strobili protect the seeds as they develop. This can take from four months to three years, depending on the species and environmental conditions. Some species of conifer need fire to release their seeds. These cones, in particular, will stay tightly closed for 60 to 80 years, waiting for fire.
Cones can range in size from 1/10 of an inch to two feet in length. There are male cones that produce pollen, and female cones, where pollination occurs. Both types of cones are usually found on each tree. Different species of conifer spread their reproductive cycle out over one, two, or three years.
While some plant families include thousands of species, the conifers boast only 7 or 8 subfamilies (depending on which botanist you ask) and most of us recognize even fewer. There are less than 630 living species of conifer worldwide. These include pine, cedar, redwood, larch, cypress, fir, Douglas-fir, kauri, juniper, hemlock, yew, and spruce. All conifers are in the Pinales order and the Pinaceae family. Botanists break down the subfamilies in this way:
Abietoideae - fir
Cedrus - cedars
Cupressaceae - cypress
Larix - larch
Pseudotsuga - Douglas-fir
Tsuga - hemlock [Not to be confused with poison hemlock]
Piniodeae - pine
Piceoideae - spruce
Taxaceae - yew
Other subfamilies include Araucariaceae and Podocarpaceae, both found in the southern hemisphere, Sciadopityaceae, found in Japan, and Cephalotaxaceae, mostly found in SE Asia.
While there are fewer types of conifers, these trees once covered major portions of North America and they are still the world’s greatest carbon sink. Many conifers are grown commercially for softwood lumber, paper production, and Christmas trees. Stone pines are also grown for their delicious edible pine nuts.
Conifers hold nearly all the records for height (nearly 380 feet tall), girth (over 37 feet across), volume (over 1,400 square feet), and age (4,700 years). While each conifer species is unique, they also share many common characteristics:
Pruning pines is different from pruning other trees and plants. Where most plants will sprout at the bud nearest a cut, pines only have one growing tip per branch. If this growing point is cut off, the branch will die. Pruning conifers is done before the branches actually form. As newly expanding buds, or candles, are seen, they can be allowed to grow, or they can be pinched back. Candles can be pinched back partially or completely. Candles are where the needles emerge. The bud is pinched back just as the needles begin to emerge. Where you pinch will dictate where new growth buds will form.
Looking closely at the needles of a conifer is one of the easiest ways of telling the different species apart. If the needles occur in bunches of two, three, or five, it is most likely a pine. If the needles occur singly, it is probably either a spruce or a fir. If that single needle rolls easily between the palms of your hand, it is spruce. [It actually has four sides, but you probably won’t be able to tell.] If the needle feels flat and does not roll easily, it is a fir.
Conifer pests and diseases
Bark beetles and their larva (roundhead borers) can cause significant damage to members of the pine family. Adelgids, aphids, spider mites, spittlebugs, conifer twig weevils, nematodes, and sawflies can also cause problems. The larva of several moths, including the clearwing, rusty tussock, Douglas fir tussock, spruce budworms, and the Douglas fir pitch moth all feed on conifers. These evergreens are all susceptible to canker diseases, root rot, crown rot, slime flux, and needle casts. Some of these pests can be captured with sticky barriers.
The biggest problems faced by homeowners with conifers are wind, heavy rain, and flooding. Like many other trees, conifers have a shallow root system that spreads out very close to the soil surface. Because these trees carry so much weight above ground, they can tip over. This makes it very important to install potentially large trees far enough away from structures, such as your home, chicken coop, or garage, to prevent serious harm in the case a tree falls.
Did you get a conifer during the last holiday season? If so, check out my handy holiday plant care page!
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