Rubus – Raspberry.
Family Rosaceae.
A very complex genus with around 250 species divided into 12 or 13 subgenera then sections.
Subgenus Rubus is the largest with 12 sections including Sect. Rubus.
The genus includes blackberries (Rubus ursinus and R. fruticosus) usually with black fruit
and raspberries (R. idaeus) with red fruit.
Species interbreed readily and some can form seed without fertilisation.
Hybrids include the Loganberry and Boysenberry.
There are about 25 Rubus species in Australia with 7 being native.
Commercially produced raspberries are cultivars commonly involving R. strigosus and R. idaeus
(sometimes considered the same species under the name R. idaeus).
Commercial Raspberries.
Family Rosaceae > Genus Rubus > Subgenus Idaeobatus.
The roots are perennial but the canes only last 2 years.
Canes mostly have prickles but some cultivars do not.
Primocanes, produced every year, are upright or slightly arched and unbranched.
They are up to 2.5 m long and have large leaves variously divided into 5 (3 or 7) leaflets.
In the second year side branches or floricanes grow and have smaller leaves.
These are usually divided into 3 leaflets.
Leaves are sometimes undivided near an inflorescence.
After producing flowers and fruit these canes die or are pruned out.
Leaves are on stalks with narrow stipules.
Leaf edges have teeth and are occasionally lobed.
Inflorescences are clusters of flowers on the side shoots.
Flowers are bisexual with parts in 5’s.
The 5 sepals may be curved backwards.
The white petals, up to about 6 mm long, spread outwards.
There are numerous stamens and many carpels on a long receptacle.
Commonly known as berries the fruit are an aggregate of up to 125 small drupes (drupelets)
each formed from one of the carpels.
(A drupe is a fleshy, indehiscent fruit with 1 seed that has a hard coat.)
The raspberries are about 1 cm long and consist of just the drupelets as the enlarged,
pale receptacle remains on the bush.
Using a variety of cultivars and growing conditions fruit can be available all year.
Pruning and picking are highly labour intensive.
J.F.
