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Science
Volume 40 Issue 7 • June 17-23, 2010
now in our 40th season

Island Blackberries

by Dr. Sarah D. Oktay
Managing Director UMass Boston Nantucket Field Station

I originally started writing this week’s article about our local squid AND blackberries in an effort to create a less than brilliant homage to science historian and BBC legend James Burke of the late 70s BBC documentary series “Connections.”  But I found I needed another week just to round up some of the information and sort through some controversy surrounding squid fisheries and species identification; as blackberries, as far as I can tell, do not court much controversy, we’ll concentrate on them this week.

Our succulent high bush and low bush blueberries get all the press, but in a week or two, the blackberries will be the star of the show on Nantucket. Although a bit more elusive than blueberries, blackberries are scattered around the island in well drained areas receiving a fair amount of sunlight.  At least at the Nantucket Field Station, they do very well near wetlands.


The blackberry is an edible fruit produced by any of several species in the Rubus genus (Subgenus: Rubus, formerly Eubatus) of the Rosaceae (Rose) family. The name is derived from the Latin, rubus, bramble, - from ruber, red, an allusion to red dye obtained from fruits of some of the species. Other common plants you’ll see on the island in this family are the dewberries (like Rubus flagellaris) and raspberries. The fruit is not a true berry; botanically it is termed an aggregate fruit.  In an aggregate fruit composed of small, individual drupes, each individual is termed a drupelet.  The fruit of blackberries and raspberries comes from a single flower whose pistil is made up of a number of free carpels.  A drupe is a fruit in which an outer fleshy part (exocarp, or skin; and mesocarp, or flesh) surrounds a shell (the pit or stone or pyrene) of hardened endocarp with a seed inside. These fruits develop from a single carpel (leaflike, seed-bearing structures that constitute the innermost whorl of a flower), and mostly from flowers with superior ovaries (or at least that is what they say). The definitive characteristic of a drupe is that the hard, lignified stone (or pit) is derived from the ovary wall of the flower.

Blackberries

Most brambles and all blackberry species have fan-like palmate-compound leaves—each leaf is divided into segments emerging from one point, like the fingers emanating from your palm. Each of the three to seven oval, pointed, leaflets (segments) is finely toothed (serrated) and usually dark green in color with fine hairs. Blackberry and raspberry plants may be difficult to tell apart; however, blackberry leaves are light green in color on the underside, while raspberries have silvery undersides. Blackberries bear white or pale pink colored flowers and these come out in mid-summer, the bloom of these flowers is immediately followed by the well-known fleshy berries that ripened to a black color. The same plant may bear both flowers and fruits at the same time.

Blackberry plants have thorny, arching stems called canes. The plants typically have biennial canes and perennial roots. A biennial plant is a flowering plant that takes two years to complete its biological lifecycle. In the first year the plant grows leaves, stems, and roots (vegetative structures), then it enters a period of dormancy over the colder months. Usually the stem remains very short and the leaves are low to the ground, forming a rosette. Many biennials require a cold treatment, or vernalization, before they will flower. During the next spring or summer, the stem of the biennial plant elongates greatly, or "bolts"; the plant then flowers, producing fruits and seeds, before it finally dies, perhaps heroically. In this case, the “canes” or stems of the blackberry are biennial which means they live for two years and the roots are perennial, which means that part of the plant lives for more than two years. Wild blackberry plants can live for 25 years or more. They produce vines that arise from a central crown or from buds that form along rhizomes (horizontal, underground shoots). Tips of first-year canes that contact the ground form roots at the nodes, contributing to the lateral expansion of the plant. Wild blackberry flowers are pollinated primarily by bumblebees and honey bees. The flowers can be self-pollinated but fruit set is increased by cross pollination.

Blackberry plants are considered shrubs and when fully mature become sprawling, woody and dense plants with tenacious, prickled (synonym, “ouch!”) trailing stems reaching up to five meters or 15 ft in length. As mentioned above, when any of these stems comes in contact with the ground, it gives off roots and the plant increases the area it occupies in this way.  Blackberries and raspberries are also called caneberries or brambles. Blackberries are found all over the world and comprise a total of approximately 375-500 species depending on who you ask, many of which are closely related apomictic microspecies (let’s call them kissing cousins) native throughout the temperate Northern hemisphere and South America. To begin to see how many state-specific subspecies of blackberries there are out there, go to www.sagebud.com/tag/rubus or www.gardenguides.com/taxonomy/blackberry-rubus. The genus Rubus is believed to have existed since at least 23.7 to 36.6 million years ago.

Here on Nantucket we have our own species, called Rubus bicknellii L.H. Bailey, although we most commonly see (and eat) Rubus allegheniensis. I searched the web for quite some time finding very little on R. Bicknelli except for a rudimentary listing on the USDA’s plant database (for the insanely curious at plants.usda.gov/java/profile?symbol=RUBI2&mapType=nativity&photoID=).  I was wondering if further information would be forever elusive when I stumbled across the original citation of Eugene P. Bicknell’s article “Have We Enough New England Blackberries?” from August 1910 (Bulletin of the Torrey Botanical Club Volume #37 (8) www.jstor.org/pss/2479174 in which he dramatically laments tortuous excursions into endless briars on Nantucket and the profusion of blackberry species (listing at least 15 here) with just enough differences in appearance, fruiting, flowers, and life cycle to necessitate dividing them into subspecies. Wikipedia has a dizzying array of species and subspecies and microspecies listed at en.wikipedia.org/wiki/Rubus
From a relatively obscure article I found online (www.jstor.org/stable/4033347) called “Studies in "Rubus"” by Hannibal A. Davis [Castanea, Vol. 55, No. 1 (Mar., 1990), pp. 22-30] I read the inspiring story of Hannibal A. Davis and his wife, Tyreeca E. (love their names!) who spent 40 years categorizing and collecting various Rubus species until they donated their extensive herbarium to the Carnegie Museum of Natural History. To make one’s life work revolves around one genus with so many subspecies and such complexity is a lesson in persistence.

Across Nantucket, you’ll see a variety of dewberries and blackberries sharing habitats from the sandplain grasslands to wetland edges. These species all have similar flowers and berries, which are edible in late summer. Blackberries bloom beginning in late May with the fruits slowing ripening throughout the summer. The shrub is very tolerant of drought conditions, variations in soil acidity and drainage.  Many animal species feed on wild blackberries; consequently, seeds are easily spread from one area to another in animal droppings. Wild blackberry seeds have a hard seed coat and can remain dormant for an extended period. Once seeds germinate and grow, and the plants become established, expansion of the thicket is almost entirely a result of vegetative growth from rhizomes. Over time a single plant may cover a very large area. Bird species who favor blackberry thickets include cardinals, indigo buntings, and catbirds among many others. The literature says the deer like to eat the leaves, but there must be plenty of other yummy deer forage plants here, because I rarely encounter significantly browsed blackberries.

Blackberries have been gathered from the wild for thousands of years in Europe. Blackberries are prepared into jellies, pies, made into wine and vinegar. The consumption of blackberry jelly and wine was considered to be a fine cordial from the late seventeenth century onwards, particularly when a little brandy was added to the mix. Blackberry abounds in vitamin C and the fruit is a very good source for essential dietary fiber. Since the blackberry is one of the best known fruits in Europe, country superstitions concerning the correct or auspicious time for picking blackberries still persist in many places in Europe. For example, according to a popular belief, blackberries must be picked before Michaelmas, i.e. September 29 in the United Kingdom. The belief stems from the superstition that the devil contaminates all the berries in the wild by spitting or urinating on them after this date has passed. This hatred for blackberries came from his fall from heaven being broken by a hard landing in a large heap of brambles, which I can kind of understand. Blackberries can also be a serious nuisance issue for cranberry bog managers; although I am pretty sure they don’t spit on them.

The ancient Greeks were also familiar with blackberries and they considered it to be good for treating gout; the blackberry also features in the Bible and other ancient texts. Blackberries were cultivated by Native Americans and they provided a crucial dietary component for the Pilgrims. The root-bark and the leaves are astringent, depurative, diuretic, tonic and vulnerary (useful for healing wounds).

They make an excellent alternative medicine for dysentery, diarrhea, hemorrhoids, and cystitis. The most astringent part is the root. Orally, they are used to treat sore throats, mouth ulcers, and gum inflammations. A decoction of the leaves is useful as a gargle in treating thrush and also makes a good general mouthwash. Medicinal syrup is also made from blackberries, using the fruit and root bark in honey for a cough remedy. The blackberry is known to contain a high concentration of polyphenol antioxidants, naturally occurring chemicals that can upregulate certain beneficial metabolic processes in mammals. In fact, blackberries rank at the top of lists of antioxidant-containing foods. Most blackberries sold in the U.S. are cultivated in Oregon.

On Nantucket, as the cooler cloudy days of early June lead into the sunnier warmer days of late June and July, keep your eye out for blackberries and raspberries around the island. I’d tell you where to find them, but then, well….you know the rest of the saying. Enjoying your blackberrying excursions!

 

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