Domain Eucarya
Kingdom Plantae
Division Magnoliophyta (angiosperms)
Class Magnoliopsida (dicots)
Cronquist Subclass Rosidae or Dahlgren Superorder Rosiflora
Order Rosales
Family Rosaceae

The rose family is one of the most successful plant families, with about 2000 species in about 100 genera. Rosaceae species appear in every environment on Earth, but prefer temperate to tropical climates.

Rosaceae can appear as herbs, shrubs, or trees. They have alternate leaves, often serrate, with stipules at their bases. The flowers usually have a calyx of 5 sepals and a corolla of 5 petals. They are hermaphroditic, with many stamens surrounding a compound pistil. Flowers frequently form in bunches of various forms (umbels, racemes, The compound ovaries swell into large fruits that can be fleshy pomes, as in the Pyroideae or as drupes ('berries'), as in Prunus.

The commercial value of the Rosaceae cannot be underestimated, with several genera (especially Prunus, Malus, and Rubus) being important food sources, others (Rosa) as flowers or as ornamental plantings. Many of the tree species are valuable for their hardwood.

The phylogeny of the rose family is undrgoing revisions as of this writing. What follows is a patchwork, based upon my assimilation of several sources. Species counts are difficult because of the large number of cultivars in the commerically important genera.

Subfamily Amygdaloideae, (aka Prunoideae):

Subfamily Chrysobalanoideae (often elevated to its own family Chrysobalanaceae):

Tribe Dryadeae (subfamily uncertain, see Rosoideae below):

Subfamily Pyroideae (aka Maloideae or Pomoideae):

Subfamily Rosoideae:

Subfamily Quillajoideae:

Subfamily Spiraeoideae:

Other genera:


L. Watson and M. J. Dallwitz (1992 onwards). The Families of Flowering Plants: Descriptions, Illustrations, Identification, and Information Retrieval. Version: 14th December 2000.
http://biodiversity.uno.edu/delta/

Evans, R., C. Campbell, D. Potter, D. Morgan, T. Eriksson, L. Alice, S.-H. Oh, E. Bortiri, F. Gao, J. Smedmark, and M. Arsenault - A Rosaceae phylogeny
(Abstract at http://www.botany2002.org/sympos13/abstracts/9.shtml)

Eriksson, T., Hibbs, Malin S, Yoder, Anne D. Delwiche, Charles F. , Donoghue, Michael J.
The Phylogeny of Rosoideae (Rosaceae) Based on sequences of the internal transcribed spacers (ITRS) of nuclear ribsomal DNA and the TRNL/F region of chloroplast DNA
Int. J. Plant Sci. 164(2): 197-211: 2003 avaliable online at
http://research.yale.edu/yoderlab/pdfs/2003, Eriksson et al, IJPS.pdf

An interesting question to ask someone who has any sort of background in biology is how much taxonomy affects niche. In biology, a group that evolves a feature usually finds one particular niche and stays there. For example, most birds, having evolved wings, have continued to be flying animals, penguins and ostriches notwithstanding. Most members of Ursidae, having evolved the tools to be at least partially carnivorous, maintain a carnivorous lifestyle, the Giant Panda excepted. Different biologists probably have different opinions on the matter, but in general taxons tend to radiate within a niche, only occasionally jumping outside of it. This pattern is more easy to detect in animals, where the form and function are more obviously linked, but it also holds true for plant groups, as well.

That introduction being said, Rosaceae seems to certainly follow the pattern of a family sticking in its niche. There are many different genus in the family, and some of them are speciated beyond counting, such as the genus Crataegus (the Hawthorn), which I have read as having over one thousand species. However, with all this diversity, most groups in the family follow a similar pattern. Almost all are somewhere in size between being large shrubs and small trees. Most have showy and profuse flowers that depend on insect pollination for fertilization (although many members of the family also can undergo parthenogenesis when needed), and producing much fruit that is dispersed by animals, often birds. Their range is mostly in the temperate zone, extending in a few examples to the subtropics and in a to the subarctic. Members of the family don't seem to fill an area or become climax species, instead filling in disturbed areas, such as river and stream banks and in modern time, roadsides. Their seeds are dispersed by birds, meaning they tend to grow wherever a bird happens to rest. They also, for trees and plants, have relatively short lifespans, on about the same scale as a human lifespan. There are probably exceptions to all of these rules, but this has been what I have observed about the more common members of the rose family, in some of their prime territory: the Pacific Northwest and the Rocky Mountains, during many long long walks. Whatever strategy for success the rose family discovered during the double rise of aves and flowering plants, they seem to have stuck to it and modified it for dozens of millions of years.

Within the unity of the family, there is a bit of diversity, and this is the part that often puzzles me the most. In the Willamette Valley of Oregon, for example, where members of the family seem to be one of the most common plants by road and streamsides, there are five main groups that compete with each other for valuable ditch space: the native blackberry, the (invasive) Himalyan blackberry, the wild rose, various types of Hawthorne, and the wild apple tree. I often wonder why one patch of road will be full of the fast growing invasive blackberry, while a little further on the native blackberry is still dominant. Or, when I see rose bushes surrounded by invasive blackberries, I am seeing a state of equilibrium or whether the blackberries are soon going to overtake the roses. Are Hawthorn trees and apple trees growing side by side going to both stay shrubs, or are a few of each going to turn into full fledged trees and confine the other to the shade? I do know there are a few factors that are somewhat predictable, such as the fact that roses seem to do better with cold and dry areas than the invasive blackberries do, but this hardly seems to make a difference when they are growing in a patchwork together. Some of the differences are more easy to see on larger scales: for example, in places both far to the east or far to the north of Portland, the very cold tolerant Sorbus spp. seems to take the place of Craetegus spp.. On the small scale, however, any guesses that could be made about plant tolerances and preferences seems to be slight in predictive power. It is not all a matter of curiosity, either: many species in this family are economically important, and I don't know if there is a simple answer for why the Pear is grown commercially in Oregon's Hood River Valley, while Apples are grown north of the river, on the plains of central Washington.

The only answer to this is that there is a lot to know about botany, and the more you study, the less sense things may make.

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