Tropicos | Name

Rosa L.

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Project Name Data (Last Modified On 6/2/2011)

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Project Data (Last Modified On 6/3/2011)

Contributor Text: Jerzy Zieliński

Contributor Institution: Herbarium, Institute of Dendrology, PL-62-035, Kórnik (near Poznań), Poland.

General/Distribution: A genus of c. 200 species distributed in temperate and subtropical zones of Northern Hemisphere, taxonomically very complex. The species are usually quite variable, Whi le the infraspecific differences are sometimes very subtle. The genetic barriers between many species are rather weak as a result intensive hybridization and introgression especially in the region destroyed due to the human activities. It holds also true in the case of Pakistan.

Comment/Acknowledgements: Numerous beautiful roses of hybrid origin are cultivated in gardens, square and parks, only most important, taxa are discussed in this account.

In the key and species descriptions, importance is given to both flowering short-shoots and long-shoots. In the latter case the prickles are primarily considered. The orifice is wide wh en it is at least 1/3 of the disc diameter.

Taxa doubtfully recorded:

Rosa glutinosa L. – recorded from Baluchistan (R.R.Stewart, l. c. 1972) – probably a form of Rosa webbiana Wall. ex Royle s.l., with stems covered with acicles.

Rosa glutinosa x Rosa moschata – reported from Baluchistan (R.R.Stewart, l.c.)

Rosa hemisphaerica J. Herrm. – reported from several places in the North (R. R. Stewart l.c.) – probably Rosa foetida or another yellow-flowered species.

Rosa gracilliflora Rehder &Wilson – reported from Kashmir (R.R.Stewart l.c.) – probably a form of Rosa macrophylla.

Rosa platyacantha Schrenk – reported from Gilgit (R.R.Stewart, l.c.), but this info rmation is not documented by herbarium specimens. It is a central Asiatic taxon, closely related to Rosa kokanica, which generally differs from it by glandular leaflets only. It is quite possible that both taxa are conspecific. Rosa platyacantha is also related to Rosa ecae but the latter species differs by being usually smaller in all its parts and by h aving glabrous styles below the stigma. Rosa moschata J. Herrm. – see discussion under Rosa brunonii.

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1.	Stipules adnate to the petiole at leat at 1/2 of their length, persistent.

2.	Sepals and petals 4.

Rosa sericea

2.	Sepals and petals 5.

3.	Styles united in a distinct column (often broken in fruit). Orifice very narrow. Flowers usually in panicles. Stems climbing or arching.

4.	Stipules pectinate or deeply dentate, with ± long fringes on the margin. Flowers small, c. 20 mm in diameter (planted or rarely escaped).

Rosa multiflora

4.	Stipules entire or indistinctly serrate, without fringes on the margin. Flowers larger (wild in the North).

Rosa brunonii

3.	Styles free. Erect shrubs, if stems arching then flowers solitary or few.

5.	Flowers white, small, often in panicles. Styles densely hairy forming compact head. Stipules narrow with erect auricles. Prickles usually curved. Fruit small, spherical. Sepals entire, often caducous together with the top of hypanthium.

Rosa beggeriana

5.	Plants with different combination of characters.

6.	Flowers yellow, sometimes flushed with red. Stipules narrow, with abruptly diverging auricles (upper free part).

7.	Styles glabrous or sparsely hairy below the stigma, forming loose head. Sepals patent or reflexed in fruit. Flowers very small, pure yellow. Stems usually zigzag, densely prickly.

Rosa ecae

7.	Styles densely hairy, forming large compact head. Sepals erect or ascending in fruit. Flowers medium-sized. Stem ± straight, not zigzag.

8.	Sepals ± dilated at apex. Flowers often flushed with red. Fruit red wh en mature.

Rosa foetida

8.	Sepals not dilaed at apex. Flowers pure yellow. Fruit brownish wh en mature.

Rosa kokanica

6.	Flowers of another colour. Stipules broader or with straight, not diverging auricles.

9.	Outer sepals with lateral lobes, deflexed and normally caduceus in fruit. Styles shortly protruding above the disc, glabrous or loosely hairy. Orifice narrow, less than 1 mm in diameter (less than 1/3 of the disc diameter). Flowers single. Fruit well developed. Stems usually arching.

Rosa canina

9.	Plants with different combination of characters.

10.

Wild plants. Flowers single. Styles densely hairy, forming compact head. Sepals entire. Fruit usually well developed, entirely filled with numerous well formed achenes.

11.

Leaflets (7-) 9-11, usually elliptic or obovate, serrulate, with more than 8 lateral veins. Prickles uniform, infrastipular.

Rosa macrophylla

11.

Leaflets 5-7 (-9), variable in shape, elliptic to roundish, grossly serrate, with 5-8 lateral veins. Prickles often mixed with acicles, bristles or stalked glands.

Rosa webbiana

10.

Cultivated plants, sometimes escaped from cultivation. Flowers often double or semidouble. Styles usually loose, often distinctly protruding above the disc. Sepals usually lobed. Fruits often undeveloped or if so then usually with few well formed achenes.

12.

Leaves persistent, leaflets glossy and deep green above, hairless beneath except for the downy midrib.

Rosa chinensis

12.

Leaves deciduous, leaflets dull green aboe, distinctly hairy beneath.

1.	Stipules free or adnate at base, caducous.

13.

Flowers in corymbs, small, up to 25 mm in diameter, fruit small, up c. 10 mm in diameter, smooth. Leaflets 3-5 (-7).

Rosa banksiae

13.

Flowers solitary, much larger, fruit large, bristly. Leaflets 3.

Rosa laevigata