'R. macrocarpa' rose References
Article (newsletter) (Nov 2017) Page(s) 18.
But for brief intervals in England and the U. S., by the end of 1910, Wilson had spent nearly eleven years in China. That year in the Red Basin regions of north-central Sichuan, he several times came across R. indica, the Tea rose. The first he saw were “spontaneous plants . . . in fruit” above a ravine along cliff tops in “a rocky defile.” He continued to find theses shrubs commonly on waysides, streamsides, and cliffs, but also in drier areas where trees were scarce but where abelia, privet, honeysuckle, and spirea grew and beyond Songpan above 3000 feet. These varied locations suggest the versatility and durance of Tea roses.
The flowers that Wilson identified as R. odorata var. gigantea “vary from white to yellow or pale buff or to pale pink.” In thickets and woodland edges, the plants become tall, rampant climbers, while on open plateaus they become arching bushes about six feet high. Wilson predicted in 1917 that odorata’s yellow and buff-colored forms would become the most valuable “in the evolution of yellow roses.”
Newsletter (Feb 2012) Page(s) 8.
[From "China in California: Dr. Wang at Quarryhill", by Darrel g.h. Schramm, pp. 8-9]
Dr. Wang pointed out several suppositions or facts. The R. gigantea in California, he said, seems to be the India form, not the China variety
Article (magazine) (2011) Page(s) 158.
The other three varieties [of Rosa odorata] (aside from the typical variety) have double to semi-double-petaled flowers, are found mainly in human-disturbed areas in the Yunnan province of China and are occasionally cultivated in other areas
....Rosa odorata var. gigantea (2n = 2x = 14; Jian et al. 2010) has single-petaled, White to creamy flowers. It is naturally distributed in the Yunnan province of China and adjacent regions of Myanmar, Thailand, and Vietnam (Ku and Robertson 2003).
Table 1 The main morphological characters, distribution information, and chromosome number of varieties of R. odorata and R. chinensis, with respective names taken from Hurst's (1941) descriptions
r. odorata var. gigantea; 2n = 2x = 14; Single, White; Yunnan in China; Myanmar; N Thailand; N Vietnam
Booklet (2009) Page(s) 28.
Diploid....R. odorata var. gigantea, heterozygous loci 35% [Provenance: Quarry Hill Botanical Garden, Glen Ellen, CA, 2002.065 cultivated form]
R. odorata var. gigantea, heterozygous loci 48% [Provenance: Quarry Hill Botanical Garden, Glen Ellen, CA, 2002.218A cultivated form]
R. odorata var. gigantea, heterozygous loci 78% [Provenance: China]
Booklet (2009) Page(s) 38-39.
All of the roses in the study classified as Tea Roses were included in this [Tea Rose] cluster, as well as one accession of R. odorata var. gigantea (OG3) sent directly from China [ex Flower Research Inst., Yunnan]. It does not seem unlikely that OG3 might group here, since it is thought to be one of the original parents of the first Tea Roses (Harkness, 1978), but what is odd is its low similarity to the other accessions said to be of this same species in cultivation in the United States (OG1 and OG2) [ex Quarry Hill Bot. Garden]. OG1 and OG2 group with each other at a similarity of 0.83, while OG3 only has 0.19 similarity with OG1, and 0.21 with OG2. Another recent study found that an R. odorata var. gigantea and R. odorata var. erubescens had an SSR-based similarity coefficient of ̴0.64 (Tang et al., 2008). The large difference in similarity levels could be caused by several factors. It is possible that the Chinese source used in this study may more closely represent the actual species in its wild condition, and that the U.S. source of this species, which is of cultivated origin and far removed from collection, may be the seed grown results of natural or artificial hybrid rather than representative of the wild R. odorata var. gigantea. The opposite could also be true though, with the U.S. source (35 & 48% heterozygous loci) being cultivated offspring of a wild representative of the species, and OG3 (78% heterozygous loci) a cultivated variety of R. x odorata and an example of one of the first Tea Roses bred in China, rather than the wild species native to that country. The chloroplast sequence data gives additional information on these accessions.
Article (magazine) (2009) Page(s) 31.
R. gigantea Collett Source RJBM [Réal Jardin Botanico Madrid] Chromosome Number 14
Article (misc) (Jun 2007)
R. gigantea .... is perhaps the largest of all wild rose with the most extensive growth, up to 20 meters, the giant stems thicker than a man’s arm, very large flowers up to 15 cms. across, and big round hips 2 ½ cms. across. The numerous prickles are also of giant size.
The five-petalled flowers are quite a deep yellow when opening, fading thereafter to ivory and cream. The yellow pigments seem dominant in the plant, as even the hips ripen to yellow rather than the more usual orange-red. And these hips are eaten by the locals. They are sold along with other vegetables and fruits in the bazaars in north-east India.
We found this plant at around 2200 meters on the footpath to Mount Sirohi, east of Ukhrul town in Manipur State, climbing into trees, which is their normal pattern of growth.
Sir George Watt, Surveyor General of British India, who first discovered this rose species in 1882, remarked that the flowers of the rose climbing through forest trees looked like golden magnolias, when seen from a distance! I like to think that the specimen we found was the same as did Sir George Watt !!!
Though Sir George Watt was the first to discover the species in Manipur, the name ‘R. gigantea’ was first published by Sir Henry Collett, through M. Francois Crepin. Collett found the plant in the Shan Hills in Upper Burma, now Myanmar.
There has been some speculation whether there is any genetic difference between these two finds, arising out of the fact that the buds and flowers of R.gigantea Collett are white, whereas the plants from Manipur, to which the discoverer, Sir George Watt, gave the name R. macrocarpa, have flowers which tend more towards a creamy yellow, especially in the bud stage.
The location where the rose was found in Manipur, is about 5o further north, and altitude around 500 meters higher than the Burma specimen, which again may, or may not , be significant.
Interestingly, seedlings raised from seed collected in Manipur in the wild, show considerable variation in flower color especially in the bud stage. Some of plants bear buds of quite a dark shade of yellow, whereas others are cream. But these variations disappear at the fully open stage, where the flowers are cream. This perhaps indicates that speculation on whether the Manipur and Burma forms are genetically different are premature, in the absence of DNA studies.
Crepin himself considered the two to be the same rose. But we can hope that the Manipur type is at least marginally cold hardier.
A feature of this rose, apart from the flowers, is the lovely foliage, evergreen but a compelling shade of bronze as it unfolds, maturing to a shiny dark green. Absolutely free of black spot or mildew.
In my garden, in Kodaikanal, R. gigantea has climbed the cypress trees, which are quite tall, 15 meters and more, and in the flowering season – which extends form November to February—makes a very attractive display indeed.
Article (magazine) (2007) Page(s) 404.
Table 1. Comparison of key volatile components in representative cultivated Chinese roses and species. [adsorption volume by Solid Phase Microextraction (peak area, x10')]
Article (magazine) (2007) Page(s) 401.
DMMB [1,3-dimethoxy-5-methylbenzene] is a key component of the fragrance element commonly referred to as 'Tea'. This component...has a relaxing effect (sedative properties) and is originated from Rosa gigantea Collett native to southwestern China throught Myanmar (Shoji et al., 2000; Yomogida, 2004).
Article (magazine) (2006) Page(s) 22.
...The flowers of R. gigantea emit almost exclusively DMT [3,5-dimethoxytoluene]...