About Species Roses
A paper presented at The American Rose Society National Convention, Nashville, Tennessee, October 1990
By H. Scott Hansen
Remember your high school biology? Kingdom, phylum, class, order, family, genus, species? Roses go thusly, Plants; Gymnosperms; Dicotyledons; Rosales (Order); Rosacea (Family - includes about 100 genera); Rosa (Genus); and Species (what we are here to talk about).
Rosa is subdivided into three sub genera, Hesperrhodos, Platyrhodon, and Eurosa with one near genus, Hulthemia.
Eurosa is sub-divided into eleven (11) sections: Banksianae; Bracteatae; Caninae; Carolinae; Cinnamomae; Gallicanae; Indicae; Laevigatae; Leucantae; Pimpinellifolae; and Synstylae.
Species Roses (always plural) are the wild and native roses, the primogenitors. When we see the term species roses we think of wild roses.
The majority of species roses are from Asia, and especially China, where over millions of years of geologic changes the stable temperate land mass was propitious for their evolution. It is generally accepted that Rosa evolved around 40 million years ago (maybe twice that long). Definite rose leaf fossils have been found in Asia, Europe, and North America. No species or fossils as an original plant has been found in the Southern Hemisphere.
The Asian species gave us repeat bloom, yellow flowers, real red-reds, and the climbing or trailing growth.
Species is an indefinite and elusive term what with sub-species and mutations (sports). Botanists who specialize in classification are known as Taxonomists and consist of the "joiners" (those who go for fewer species) and "splitters" (those who go for more species). One authority came up with the number of species as 4,266 for which an unkind colleague remarked that he must have found several on a single plant. The numbers range from 150 to 300. Modern Roses 9 contains somewhere over 250 listed species with Modern Roses 8 listing 23 (not in MR 9) that almost have to be species. There are between 12 and 20 North American species.
The concept of species is not clear-cut and a definition is not agreed upon. Perhaps the most generally agreed upon definition is that species roses breed true to themselves and this is generally true.
A group of like plants growing in an area where there has been no outside influence reaches a stable steady-state. Just because a rose is wild and native does not make it a species. Over the millennia, even millions of years, somewhere in the past there could have been cross pollination where the dominant genes have had ample time to settle to achieve a look and a character of their own.
The potential may be there for all sorts of future offspring. Many "species" are natural hybrids that have achieved stability.
Dr. Charles A. Walker, Jr's. note in Modern Roses 9 (page 263) at the beginning of the species listing may be of some help. "The concept of a rose species is difficult for most rose growers to comprehend, since we generally think in terms of cultivars. Given enough practice it is usually easy to distinguish one cultivar from another. Since roses are vegetatively propagated (budded, rooted from cuttings, or tissue cultured), each cultivar is actually a clone -- a group of genetically identical plants. Thus, under the cultivar concept our roses are neatly divided into separate, non-overlapping groups and each group consists of plants which are identical to each other.
"On the other hand, the concept of species is not so clear-cut. A definition of species is not universally agreed upon, but a rose species is best thought of as a group of cross-pollinated plants grown from seed in the wild. Therefore, they are not all genetically identical, as is the case with a cultivar. In nature, two species are separated by physical or genetic barriers which prevent the members of one species from interbreeding with those of the other. This results in two types of variation: (1) that among several species and (2) that within a particular species. It is this second type of variation which is difficult for cultivar-oriented rose growers to grasp. Two plants of the same cultivar can vary somewhat due to climate and culture, but two plants of the same species can vary much more. We can see differences in number of petals, color, prickliness, stature, or any of several traits -- so much so that it may be hard to decide whether they are in fact members of the same species. This is particularly true for wide-ranging species such as Rosa carolina."
Dr. Walker's point about cultivars being asexually reproduced where chromosome and gene arrangement remain stable while species are sexually reproduced with the resultant chromosome and gene juggling is bound to produce some variations in the offspring. Rosa's inherent tendency to "sport" has produced more species. A sport of a species is still a species, so species are still being produced.
An interesting example of Dr. Walker's item No. 1 above could be the only American species in the section Synstylae (and a climber), Rosa setigera. Most of the Synstylae species are white; most of the widespread American species (Carolinae and Cinnamomae) are pink. Guess what, R. setiera is pink!
Some species have sported in several ways to have names, "alba" (white flowers); "lutea" (yellow flowers); "rubra" (red or purple flowers); "plena" (double form); "inermis" and "denudata" (unarmed); "spinosa" (enlarged prickles); normalis" (wild form single flower); to name just a few.
R. rugosa, N.E. Asia - Mauve. R. rugosa alba, - White R. rugosa alba-plena, - White; Double. R. rugosa chamissoniana, nearly free of bris¬tles. R. rugosa kamtchatica, 1770, Flowers & fruit smaller. R. rugosa plena, - Double form. R. rugosa rugosa rosea, - Pink. R. rugosa rubra, large, brilliant magenta purple.
This is an illustration of Dr. Walker's 2nd point above.
Many authorities mention a so-called 2nd generation "species" roses to include 2 important types--the Albas (R. canina x R. gallica) and the Damasks (R. moschata x R. gallica and R. phoenicia x R. gallica).
The Albas and Damasks were prevalent in ancient historical times and are often equated with the species roses. However, they are not species roses nor are the Centifolias.
We usually think of species roses as five petal singles somewhat like an apple blossom, but larger. However, R. Omiensis ptericantha has only 4 white petals again showing that almost all generalizations about Rosa have exceptions.
Colors of species, taking an average from several authorities, range from (approximately):
Pink--45%, White--30%, Red--12%, Yellow--7% Maroon-lilac-Mauve--5%.
Modern Roses 9 lists very few that may be considered color blends in species:
R. corymbulosa, red with a white eye. R. foetida bicolor, orange-scarlet, yellow reverse. R. giraldi, pink with white center. Jaune Bicolor, yellow streaked red. H. persica, buttercup yellow with a scarlet eye, yb.
When a bush type rose sports to become a climber it doesn't bloom as much. Climbing sports are not as recurrent as their bush counterparts. Sometimes natural climbers upon sporting to a bush may become somewhat recurrent.
The known species roses in the section Indicae are continuously recurrent.
Occasionally recurrent species roses are found in the Bracteatae section, a few in the Carolinae section, some in the Cinnamomae and Synstylae sections, and the double form only in the Platyrhodon section.
Sporadic recurrent species roses are found in the Pimpinellifolae section. My "Austrian Copper" frequently has scattered blooms in July and August
Those sections which seldom repeat are Banksianae, Caninae Gallicanae, Laevigatae, Leucantae (?), Hesperhodos, and Hulthemia.
Half (7) of the sections have stipules firmly joined along the leaf stalk (Caninae, Carolinae, Cinnamomae, Gallicanae, Indicae, Pimpinellifolae, and Synstylae). Bracteatae and Laevigatae are joined at the base only. The two subgenera, Hesperhodos and Platyrhodon, are only partial; the near genus Hulthemia has no sign of stipules, and Banksianae stipules are termed "free", which term I don't understand as I can see none.
Again, half of the sections have bracts (not the same ones that have stipules); Bracteatae, Caninae, Carolinae, Cinnamomae, Gallicanae, Indicae, and Leucantae. The rest have no bracts.
There are about a dozen (12) listed in MR 9 as "Double" and seven (7) more as "Semi-double"; almost all of these have a single form also.
The earliest historical record we have of rose cultivation is from China, 5,000 years ago. We are deeply indebted to those ancient Chinese gardeners, knowing nothing of Mendel's laws or about chromosomes, but who picked out the seeds of the better roses they grew and replanted them. They thus en¬couraged doubleness, repeat bloom, and other desirable qualities.
Sometimes the individual who discovered or introduced a species rose has been honored by having their name attached, "andrewsii", "watsoniana", "willmottiana" and "kordesii".
Those species roses entering into the mainline of modern rose development are those in the sections, Gallicanae, Indicae, Caninae, Synstylae, Pimpinellifolae, Cinnamomae, with perhaps a few others (especially in the modern shrub types.)
The species roses contain many features that are desirable, adaptability to soils and environment (R. rugosa); disease resistance (R. banksia, R. laevigata); deep yellows (Pimpinellifoliae); non-bluing reds (R. moyesii); thornlessness (R. blanda); powerful fragrance (many); vigorous growth habit (R. banksia, R. wichuraiana and many others); and so on.
Modern shrubs, often a combination of species and modern roses have incorporated some of these qualities.
One of the best roses for hedges is Rosa multiflora, sometimes used as a crash barrier in highways. With plants set one foot apart, it is said to be "horse high, bull strong, and goat tight." R. multiflora is an example of a species roses which has escaped and is now a noxious weed in parts of the United States. We've seen the term "naturalized" when referring to R. bracteatae and R. laevigatae. This means these two also "escaped."
Of the eleven sections, two sub-genera, and one near-genus, several have only one solitary distinctive representative. Others only consist of climbers. There is no complete agreement on these sections among authorities.
In 1994, H. Scott Hansen, the author of this article, gave a disk full of his articles to Kitty Belendez with permission to publish them. H. Scott Hansen is now deceased.
© Copyright Estate of H. Scott Hansen. All rights reserved.