This is a great year for raspberries. The little patch in our backyard is producing a dessert every night, and out in the woods the canes in the bramble thickets are heavy with fruit. I make plans for our backyard berries, plans for raspberry tarts and for berries dressed with sweetened yogurt drained of its whey and enlivened with lime juice and mint leaves. Somehow I never get to these plans. Fresh raspberries–picked, washed, and drizzled with honey–are better than any of my raspberry-gilding ideas. An old saying goes, “Doubtless God could have made a better berry than the strawberry, but doubtless God didn’t.” The saying is of course wrong. He did make a better berry–the raspberry.
When I was a kid we had a good-size raspberry patch in the backyard. My mother used to send me out to pick berries for supper. I had to pick a ton, because most of what I collected I ate on the spot.
Twenty-some years ago, my wife Glenda and I used to spend long periods of time on 40 acres of scrubby second-growth woods we owned in Taylor County, Wisconsin. Raspberries grew beside the gravel roads in the neighborhood. The roads carried maybe 12 cars a day. We could pick quarts of berries without ever breathing the dust of a passing car.
When we lived in Douglas County, Wisconsin, one of our neighbors had a small herd of guernsey cows. Guernseys don’t produce as much milk as Holsteins, but what they do produce is very rich in butterfat. We used to trade fresh berries for fresh cream so both households could enjoy the combination.
What I am saying is that I really like raspberries. However, my love for them is nothing compared to the regard botanists feel. For botanists, raspberries are not just a wonderful dessert. They are a career.
Gray’s Manual of Botany lists 205 species of the genus Rubus, which includes raspberries, blackberries, thimbleberries, and other brambles. (For the sake of convenience I will use the term “raspberry” to cover the lot.) The manual deals only with eastern North America, and Rubus grows throughout the northern hemisphere and in mountains as far south as South America. The worldwide species total must be enormous. Just thinking of names for all these plants would be a considerable undertaking.
Many of our eastern Rubus were given their names by Liberty Hyde Bailey, a botanist born in 1858 who wrote voluminously on the genus. Bailey was careful to give credit to the discoverers of the various species he described, so we have R. maltei, named for a Swedish botanist, R. rosagnetis for a nun named Sister Rose Agnes Greenwell, and R. whartoniae for Mary E. Wharton. We also have assorted geographical names, including indianensis, wisconsinensis, michiganensis, and, even more localized, kalamazoensis. Bailey could also get positively whimsical, attaching the name licens (unrestrained) to a spreading species, temerarius (ill-advised) to a species he had originally misidentified, and compos (master of its domain) to a species that tended to form extensive thickets. Bailey was himself honored with the designation Rubus baileyanus, given to a species found in open, sandy woods. All of these names are attached to plants that produce five-petaled flowers–almost always white–that give way to fruits called drupelets. Drupes are fruits, like peaches and olives, with single hard stones at the center. Drupelets are aggregations of very small drupes. In raspberries the stones are small enough to be readily edible but hard enough to give a noticeable rasp to the sensation of eating a berry.
Raspberries are mostly herbaceous, but some of their canes can get a bit woody. First-year canes (primocanes) carry only leaves. The second-year canes (floricanes) carry flowers and fruit. In some species the canes are erect, in others they grow in arches, and in still others they lie along the ground. In some species the plants spread by sending up shoots from roots that spread horizontally underground. In others the arching canes take root at their tips. Either way, raspberries can form dense thickets that crowd out other plants, provide shelter for rabbits and other small animals, and offer concentrated food sources for everything from small birds to bears. Most raspberries are prickly and therefore protected from both grazing and browsing animals.
You might reasonably ask why there are so many different kinds of plants belonging to the genus Rubus. The answer is complex, incorporating as it does both botanical and historical factors. We could simply blame the splitters.
Taxonomists, the people who classify plants and animals, have traditionally been divided into splitters and lumpers. Splitters tend to see tiny differences as significant enough to justify the naming of a separate species. Lumpers accept considerable variation within a single species. Maybe the genus Rubus is just a case of splitters going wild.
However, M.L. Fernald, the author of Gray’s Manual of Botany, describes the genus Rubus as a “most difficult group.” His reading of the situation is that “our few original wide-ranging, essentially unvarying and ancient species have greatly commingled since extensive clearing of the land and have crossed, producing somewhat localized but rapidly spreading offspring.” He calls these offspring “incipient ‘species.'”
Even the indefatigable Bailey admitted that when he used the term “new species” in connection with the genus Rubus he was not using the term in “its old formal, final sense.” In other words, the dramatic changes we have produced in the landscape have thrown together previously separated populations and created hybrids that never could have existed before. Fernald expected that these new forms would “increase with time and new crossings.”
The changes we set in motion are far from over. Textbooks define species as reproductively isolated groups. Even if R. kalamazoensis and R. indianensis encounter each other they shouldn’t be able to reproduce. If they can, then maybe those “ancient species” were themselves only “incipient.” Though separated by circumstances, they might, if thrown together, produce offspring as readily as a Frenchman and a Potawatomi.
Complicating the issue is the fact that Rubus is a genus in the rose family. It is a difficult group within a larger difficult group. The family includes hawthorns, a group of shrubs that may include 103 species–or far less or far more. Members of the rose family seem to have a strong tendency to create apparently sterile hybrids that reproduce by vegetative means such as root suckers but not through seed. Plants have an edge here. Mules, for example, have to be produced each generation by the crossing of a horse and an ass. If mules were plants, they could send up root suckers that would produce new individuals without all the rigmarole associated with sex.
Swink and Wilhelm, in Plants of the Chicago Region, treat the brambles about as simply as one can. They lump several different forms into each species, ending up with ten natives. They place both R. baileyanus and R. rosagnetis, along with some others, in a species they give the common name “one-flowered dewberry.” This humane approach greatly simplifies the lives of field botanists. The most visible of their species is the common blackberry, which is currently feeding birds and passing hikers on natural lands throughout the region.
For land managers in the Chicago area, brambles include everything from aggressive weeds that drive out every other plant to rare and endangered species that need protection. No less than three of the ten species described by Swink and Wilhelm are on the endangered or threatened lists in Illinois. Even the ability to hybridize freely and form dense, self-protecting thickets has not been enough to keep all the brambles safe.