From "A Condensed History And Classification Of the Genus Rosa": Around 5,000 species of roses have been described, but by far the greater majority of them are not valid species.... The late G. A. Boulenger worked on the Old World species... Boulenger recognized 105 species. In this country, Erlanson investigated the situation and concluded, after ten years of intensive study, that... the North American Flora can be reduced to 18 species. There are two duplications in the two lists, so the latest revision, therefore, reduces the number of valid species in the Old and New Worlds to 121.

Over half of the roughly 200 rose species in the world come from China. See also GLOSSARY: European Wild Roses.

[From The Rose Garden, p. 25:] In 1820 the "Rosarum Monographia," by J. Lindley, appeared, in which many species besides sub-species are described, and thirteen of them figured... Lindley's species number seventy-six, or one hundred and one if we include doubtful species... In the Catalogue of Messrs Loddiges & Sons, 1826, no less than 1393 species and varieties of Roses are numbered as existing in their nursery at Hackney, and there is an additional list of 66 "Chinese with varieties and Hybrids..." In Sweet's "Hortus Britannicus," published in 1827, there are 107 species given, and 1059 varieties, the greater portion of the latter being French or Gallica Roses...

[From Gardening with Old Roses, p. 20:] Wild or species roses are the parents of all the roses we grow today... They are almost all single flowers with five petals (R. sericea being the only species with four), blooming for a few brief weeks, their delicate fragrant flowers followed by glowing hips, all amid generous foliage.

[From Gardening with Roses, by Judith McKeon, p. 16:] Species roses tend to be tough landscape plants and are useful in spots where more delicate roses might fail; sites in blazing sun, dry city gardens, and hot spots near paving are all difficult planting situations where resilient species roses will fare well.

[From Roses, by Eleonore Cruse, p. 7:] Several hundred wild species have been recorded, although so far there is no official inventory. Most have single flowers and decorative fruits. They never suffer from disease, and look attractive all year round.

[From The Art of Gardening with Roses, by Graham Stuart Thomas, p. 11:] there are some 150 species wild in the Northern Hemisphere; some as low as 1 ft (30 cm), others ascending to 60 ft (18 m). Of these the vast majority are of pink or mauve with a few white; yet a few more are of pale yellow, from Asia. Any tint of red is confined to one Chinese species and to abnormal "sports" of two species that are normally pink or brilliant yellow.

[From A Heritage of Roses, in the Foreword written by Graham Stuart Thomas, p. 7:] some 150 species with five petals only grow wild around the Northern Hemisphere. Of these only a mere handful have become the darlings of horticulture...

[From The Rose Garden, by William Paul, pp. 3-4:] It is a remarkable fact that Australia has naturally no roses, and none have yet been found wild very near to or south of the Equator... It is in the temperate regions of Asia, and throughout Europe generally, that those species abound from which nearly the whole of the present garden varieties have sprung. But if we extend our view, we find some growing on the mountains of North America, whose tops are covered with eternal snow; and others in the dreary wilds of Greenland, Kamtschatka, and Iceland; while in Siberia there are several interesting species. On the other hand, if we turn to warmer climates, we discover that Mexico, Abyssinia, China, Persia, India, and Egypt have their Roses; and even on the outskirts of the mighty Sahara one species is found, gladdening the approaches to the desert with its clusters of white flowers.

[From Roses of America, by Stephen Scanniello and Tania Bayard, p. 38:] There are at least two hundred types of wild roses in the world. We call these species roses, the roses that occur naturally and from which all other rose varieties are derived. Their simple flowers are usually composed of five petals, and they bloom once a year, in the spring.

[From The Admirable Old Roses, by J.R. Carabin, p. 195:] The species roses are the original forms, unstained by hybridization. They vary in height, are extremely vigorous and usually cold hardy. They have single blooms which are followed by conspicuous fruits loved by the birds. Species roses will attain their full splendor in poor soil. They bloom in spring and early summer in great profusion.

[From Botanica: the illustrated A-Z of over 10,000 garden plants, p. 772:] Rose species are divided into 4 main groups: Hulthemia, Hesperhodos, Platyrhodon and Eurosa. The first 3 groups include only 5 species; the rest belong to the Eurosa group, which is itself divided into 10 sections.

[From Roses: An Illustrated Encyclopaedia and Grower's Handbook, by Peter Beales, pp. 4-5:] The species of the genus Rosa can be conveniently divided into four groups, each from geographically defined areas of the northern hemisphere where they are to be found growing wild. These areas are Europe, Asis, the Middle East and America... all wild roses have single flowers comprised of five petals; except one, R. sericea, which has just four. All, in their natural habitat, will reproduce true-to-type from seeds when pollinated by themselves or others of the same species...

[From Asia's Part in Rose History, by Dr. Wilber Stout, p. 112:] the specie roses of China are about equal to that of both Europe and North America.

[From "The Old Problem of Species in Rosa" by Dr. Eileen W. Erlanson Macfarlane in ARA (1965) at pp. 150-160: The best definitions of a Linnean species are those of (1) Vavilov (1931) "A separate morpho-physiological system connected in its genesis with a definite environment and area"; and (2) Babcock (1930) "A natural group possessing relative stability, combined with a definite tendency to vary"....Among American rose species there are two types: (A) Easily delimited Linnean type species, which are quickly recognized....these have a circumscribed area of distribution: e.g., R. setigera, R. foliolosa, R. nitida....(B) Highly variable, called polymorphic, species, collective species or species complexes, which range over thousands of miles. They exhibit parallel variations, that is: tall and dwarf; armed and unarmed; pubescent and naked foliage; no glands or grandular leaves; globose or pear-shaped hips....Many of the minor variants have been given specific [mean species] names. They hybridize in the field....This free crossing in areas where the ranges and flowering times overlap naturally causes another maze of variant types, as well as pollen and seed sterility...> From the beginning I noticed that the phenology of wild roses was helpful in distinguishing species. That means the date of the opening of first flowers and the time taken for the hips to ripen.