[From Old Roses and English Roses
by David Austin, p. 69:] The China Roses have smooth leaves and few thorns
[Ibid, p. 72:] China Roses differ in character to most other garden roses; even to those unnumbered masses that are their heirs. They are altogether lighter in growth. This is perhaps because they are diploid, whereas the majority of garden roses are tetraploid; that is to say their cells contain two sets of chromosomes, whereas it is more usual to have four sets, resulting in larger cells and therefore heavier growth. China Roses have airy, twiggy growth, and rather sparse foliage, with pointed leaves, like a lighter version of a Hybrid Tea… They have an exceptional ability to repeat their flowering, and are seldom without blooms throughout the summer. Their colours are unusual in that they intensify with age, rather than pale, as is the case with European roses.
[From The Quest for the Rose, by Phillips & Rix, p. 100:] They are usually small shrubs with red, pink or white flowers … When crossed with the original Tea Rose, 'Parks' Yellow Tea-scented China', they gave rise to Teas. They were also crossed with other groups to introduce their repeat-flowering character to European roses. One of the original introductions, 'Old Blush', remains an excellent garden rose and some early hybrids such as 'Hermosa' (1834) and 'Mutabilis', which has been known since 1896, are still widely grown today.
[From Gardening with Roses, by Judith McKeon, p. 22:] The breeding and cultivation of roses have been integral to Chinese gardening for five thousand years. Through selection and hybridization, Chinese breeders enhanced the repeat-blooming character of Rosa chinensis and produced hybrids noted for their continuous bloom. When official trade routes opened between Europe and Asia, China roses were imported to the West, appearing around 1800.
[Ibid, p. 23:] China-influenced roses are not as hardy as once-blooming old roses, and, like their modern successors, they may be either disease-resistant or disease prone.
[Ibid, p. 24:] China roses are rarely out of bloom and typically produce cupped flowers that deepen in color with age rather than fading. Bushes are relatively small, wiry, and airy, with smooth interstems and shiny, pointed leaves that are tinged red when they emerge... Fragrance is variable and not as intense as in other old roses.
[From Gardening with Old Roses, by Alan Sinclair and Rosemary Thodey, p. 27:] An attractive feature of the Chinas which was passed on to the Bourbons is their characteristic of deepening in colour instead of becoming paler and washed-out looking as the flowers age.
[From The Art of Gardening with Roses, by Graham Stuart Thomas, p. 21:] The first hybrids of any importance to crop up from the China roses were yellowish -- the old Noisette and Tea climbers ('Lamarque', 'Desprez a fleur jaune','Celine Forestier', 'Gloire de Dijon' and 'Alister Stella Gray'.
[From A Heritage of Roses, by Hazel le Rougetel, p. 44, something that might shed some light on the hardiness of China Roses:] On 4 December 1838, John Lindley, then secretary of the Horticultural Society, read a paper on the effects of the great frosts of 1837-8, when most China roses [only 40 to 50 years after the first China Roses were imported to England] were destroyed. [Le Rougetel says:] Today, I find that well-established China roses need no protection... The foliage... is quite different from leaves of the old roses, being tinged reddish-brown, shining and pointed, on red stems with prominent, curved red prickles...
[From The Graham Stuart Thomas Rose Book, pp. 11-12:] The revolution that took place in the genus Rosa was due to the introduction in 1789 of [repeat-blooming] roses from China to Europe. [Prior to this, the European roses, with the exception of the Autumn Damasks, were once-blooming.]... The China Rose is almost alone among roses (Rosa rugosa is another notable exception) in being able to produce flowers from May to October [in England]. In warmer countries it has no resting season at all... the frail China Rose... was fused gradually with our coarser roses, resulting first in the Bourbons, Noisettes, and Boursaults, and later giving rise to the Hybrid Perpetuals...
[From The Old Rose Informant, by Brent C. Dickerson, p. 34: Jean-Pierre Vibert wrote in 1824: to Monsieur Noisette' we owe the introduction into France of about a dozen beautiful Chinas from Italy.
[Ibid,p. 26: Jean-Pierre Vibert wrote in 1824:] a person can count about a hundred Chinas and Noisettes... More than twenty-five varieties of Noisettes are taken in this number, presenting nearly all the shades from purest white down to purple -- several of which have double flowers
[Ibid, p. 89-90: Vibert wrote in 1826 about this about China roses in France:] The number of [Chinas or their hybrids] which owe their origin to the common China has grown today to more than 200... the first specimen was given to the Jardin des Plantes around the year 1800 by someone who probably got it in England; the name of this person is impossible to determine. Dr. Cartier was the second to grow it. In 1804, he grew the double variety from seed... The Chinas... are the only ones on which Nature has bestowed the property of blooming uninterruptedly...
[Ibid, p. 94: Vibert wrote in 1826:] the fruits of 'Sanguin' -- and indeed of the [purple China roses] -- come quite close to those of the Gallica...