Small-leaf bramble (Rubus parvifolius)

 

Small-leaf bramble is a perennial, small, prickly, woody type of raspberry. It can form dense cover and grow in sunny or shady areas. It sometimes causes confusion that the scientific name of small-leaf bramble (Rubus parvifolius) looks very similar to the scientific name of a native plant called thimbleberry (Rubus parviflorus).

 

Description

Appearance

Small-leaf bramble is a small raspberry/bramble plant. It is distinguished from other similar species by growing lower to the ground than other raspberry species and having rounded ends of its leaflets as opposed to leaflets with long tips.

Leaves and stem

Leaves are alternate (come off the stem one at time at each leaf node). The leaves are compound with 3 or 5 leaflets. The leaflets are up to 2.5 inches wide and have toothed edges. The top sides of the leaflets are green and do not have hairs while the undersides of the leaflets are silvery white with tiny, dense, wooly hairs. The ends of the leaflets are rounded compared to other bramble species which have more elongated pointed tips on the ends of the leaflets.

There are two stipules (small, leaf-like appendages) where the leaf stalk attaches to the stem. The stipules are hairy, narrow and up to 0.5 inches long.

The stems are green to red with short hairs and stiff, curved prickles. In the winter the stems turn reddish-brown (the stems of native raspberries turn shades of purple, red and green). The arching stems grow low to the ground and can reach 10 feet long. The tips of the stems can root if they touch the soil. The first-year stems are called primocanes and don’t produce flowers or fruit. The second-year stems are called floricanes and they produce flowers and fruits.

Flowers

Flowers are pink and have 5 small petals. They are arranged in clusters at the end of flower-bearing branches on the second-year stems (floricanes). Flowering is from mid-June into July in Minnesota.

Fruit and seeds

Fruits are small raspberries that are bright red and approximately 0.5 inches across. Raspberry fruits are composed of small fruits called drupelets and each drupelet produces a seed. Small-leaf bramble typically produces fewer drupelets per fruit than native raspberry species. Small-leaf bramble fruits are glossier than native raspberry fruits. Fruiting is mid-July into August in Minnesota.

Roots

Roots are fibrous. The tips of the stems can root if they touch the soil.

Biology

Small-leaf bramble can grow in areas with full sun to moderate shade. It can grow in semi-dry to semi-moist sites. Small-leaf bramble is a long-lived perennial. It produces fruits which can be eaten by birds and other animals which then spread the seeds. The tips of stems can root if they touch the ground, allowing a patch of small-leaf bramble to get larger.

Origin and spread

Small-leaf bramble is native to Asia and Australia. It was initially purposefully planted in the United States for fruit production and possibly also for erosion control. It was studied by plant breeders due to its resistance to common diseases of raspberry and due to its heat tolerance. It has since spread from areas where it was planted. It has only been documented in a handful of states in the U.S. and has only been found in a few counties in Minnesota.

Refer to EDDMapS Distribution Maps for current distribution.

Don’t be fooled by these look-alikes

  • Thimbleberry, Rubus parviflorus (native) – The scientific name of thimbleberry is very similar to the scientific name of small-leaf bramble (Rubus parvifolius) which can cause confusion when people are talking about these species. Thimbleberry has wide, lobed leaves (similar shape to maple leaves) and white flowers while small-leaf bramble has leaves that are split into three or five leaflets and has pink flowers. Thimbleberry has no prickles.
  • Other native blackberry and raspberry species (Rubus species), such as Allegheny blackberry (Rubus allegheniensis), black raspberry (Rubus occidentalis), and red raspberry (Rubus idaeus subsp. strigosus) – These blackberries and raspberries all have white flowers and they have leaflets with extended pointed tips at the end. Small-leaf bramble has pink flowers and more rounded tips of its leaflets.

 

Regulatory classification

This species is not regulated.

Threat to Minnesota

  • Forms a dense, matted groundcover that inhibits the growth of other plant species resulting in decreased diversity. Impacts in Minnesota are not well understood.

What you should do

One way that invasive plant seeds and fragments can spread is in soil. Sometimes plants are planted purposefully. You can prevent the spread of invasive plants.

PlayCleanGo: Stop Invasive Species in Your Tracks

  • REMOVE plants, animals & mud from boots, gear, pets & vehicle.
  • CLEAN your gear before entering & leaving the recreation site.
  • STAY on designated roads & trails.
  • PLANT non-invasive species.

Native substitutes

For horticultural raspberry information, see the University of Minnesota Extension webpage on raspberry types and varieties.

 

Control methods

Mechanical control can be done by cutting or pulling the plant by hand or with equipment such as rakes or cutting blades.

Mow the plant in June, July and August. Mowing can also be combined with herbicide application. Mowing can make it easier to access the plants for herbicide application.

Herbicide control can be done using a systemic herbicide such as triclopyr or glyphosate. Systemic herbicides are taken up by plants and move within the plant, which can kill leaves, stems, and roots. Herbicide application is most effective when applied in late September to early October. See the University of Minnesota Extension Controlling Unwanted Trees and Shrubs webpage for more detail on control methods.

Reporting

This species is unregulated, but you can add to the public information about this species by reporting new occurrences through EDDMapS.

Resources

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