Rosa Gigantea

Rosa gigantea (diploid) is a species of rose native to northeast India, northern Myanmar and southwest China (Yunnan) in the foothills of the Himalaya at 1000–1500 m altitude. As its name suggests, it is the largest species of rose, climbing 20 m or more into the crowns of other trees by means of its stout, hooked thorns, and with a trunk up to 50 cm diameter.

The flowers are white, creamy or yellow, the largest of any wild rose, 10–14 cm diameter. The hips are yellow or orange, 2.5-3.5 cm diameter, hard, and often lasting through the winter into the following spring, often still present at the same time as the next years' flowers.

Wonderful fragrance too. Mild to strong, clove, honeysuckle fragrance.

Syns:
- Rosa gigantea Collett ex Crépin
• Rosa gigantea macrocarpa
• R. macrocarpa
• Rosa macrocarpa G.Watt ex Crép. synonym
• R. odorata gigantea
• Rosa odorata var. gigantea Rehder & Wilson
• Rosa X odorata gigantea
• R. xanthocarpa• Rosa xanthocarpa G.Watt ex E.Willm. syn.

White to butter-yellow, yellow stamens. Buds - light yellow [Warm creamy to lemony white]. 5 petals. Large, single (4-8 petals), borne mostly solitary, flat bloom form. Moderate, once-blooming spring or summer. Large, long buds.

Tall, arching, climbing. Medium, glossy, light green foliage.

Height of 245 to 1525 cm. Width of 185 to 305 cm.

Zone 8 and warmer.
Very vigorous.
Benefits from winter protection in colder climates.
Flowers drop off cleanly.
Prefers warmer sites.
Shade tolerant.
Disease susceptibility: very disease resistant, very blackspot resistant, very mildew resistant, very rust resistant.
Can be grown as a climber in mild climates.
Prune lightly or not at all.

R. gigantea was collected in the Shan Hills of Burma at about 20 degrees N.latitude at an altitude of about 4000-5000 feet by General Collett.
Rosa macrocarpa was collected in Manipur State, in North east India at a higher altitude of about 6000-7000 feet and about 5 degrees further north, by Sir George Watt.
Though Sir George Watt considered R. macrocarpa to be a new species distinct from R.gigamtea of Collett, the great Belgian taxonomist, Francois Crepin considered them to be identical, after examining specimens of both. In the absence of DNA we should probably follow Crepin's observation. From the common sense point of view, it appears to [Viru] that R.macrocarpa is yellower because it grows further north and at a higher altitude, i.e. less bleaching of flower color occurs in cooler temperatures. Crepin observes that in the Shan hills district where R. gigantea grows, frosts are almost unknown, whereas when Girija [Viraragavan] and [Viru] collected R. macrocarpa in Manipur on Mount Sirohi at an altitude nearing 7000 feet. There was a fair amount of frost on the ground, in places frozen into fairly substantial lumps which could not have been merely overnight dew frozen. From the seedlings raised from the Manipur seed collected by [Viru & Girija they] noticed considerable variation in flower color especially at the bud stage. Some of the seedlings are quite a dark yellow at bud stage whereas others are just cream. This color difference does not persist when the flower opens and all the kinds are creamy yellow by the second day. "So to distinguish R.macrocarpa from R. gigantea by adopting flower color as the criterion seems to be incorrect. Pending further investigation we should perhaps consider R.macrocarpa of Manipur as only an eco -type of R. gigantea Collett. But I am hoping that the Manipur rose will prove somewhat cold hardier than the Burmese collection."

Rosa gigantea is recognized by its distinctive drooping, mahogany-colored new foliage, a characteristic it shares with Rosa chinensis var. spontanea.]
Information from Viru Viraraghavn