Plant Profile: Rubus parviflorus

Rubus parviflorus (thimbleberry)

During the fall of 2011, we planted a new woodland garden on a knoll under a canopy of oaks and japanese maples.  The area was previously mostly dead grass with an overgrown Philodendron grove.  One of the plants that we included in the woodland garden has become one of our favorites — Rubus parviflorus (thimbleberry).   Here is Thimbleberry in our gardens in November 2011 at the beginning of its seasonal dormancy and a profile of the plant is below: 

Overview

The Rubus genus consists of dicots in the form of mostly subshrubs (lacking distinctly woody stems).  These plants are members of the Rosaceae Family.  According to The Jepson Manual (TJM), there are 400 to 750 species of Rubus across the globe including the more commonly known Rubus glaucifolius (wax leaf raspberry) and Rubus ursinus (California blackberry). See the following link for distribution across the United States:  http://plants.usda.gov/java/profile?symbol=RUPA.   

Rubus parviflorus is native to California and is found throughout the state, except the desert and central valley, according to TJM.  It is generally found in partially shaded woodland environments — as it is in our gardens.  

Taxonomy

According to the Tropicos database, Rubus parviflorus was first recognized in 1818 by Thomas Nuttall (Nutt.) in The Genera of North American Plants.  Rubus parviflorus is most commonly referred to as thimbleberry, but is sometimes described as western thimbleberry or salmonberry (the latter being the more appropriate common name for a different species of Rubus).   

 Observable Identifying Characteristics

General:  Small subshrub, sometimes characterized as thicket-forming, with bright, almost lime-like leaves.   Erect to 2 to 3 feet.  Prefers regular watering (we water every 7 days if no rain).  Grows best in our gardens in part to full shade.

Leaves:  Deciduous, simple, palmately lobed, toothed margin (slight in this photo), acute tip (tapering to a point with no distinct change in the margin from mid point to tip — straight), distinct petiole (stalk connecting the leaf to the branch), lovely green.  We are just beginning to see new basal growth after winter dormacy.

Inflorescence and Flowers:  Not yet observed in our gardens, but expecting white and zygomorphic flowers on panicle-like cymes (branched flower stems emanating from a single point with flowers).  The flowers are dioecious (“imperfect” in that the male and female flower parts are not found on the same plant — so why not plant many to ensure reproduction?!).  

Stems:   A characteristic which distinguishes Rubus parviflorus from other species within Rubus is the lack of prickles (small, sharp outgrowths on the stem). 

Fruit:  Not yet observed in our gardens, but expecting to be blackberry-like (and tasty!).

Compatible Plantings:  According to Las Palitas Nursery, Rubus parviflorus is commonly found in nature along side Ribes.  We’ve planted these two in close proximity to one another.  We’ve also added Rubus spectabilis (salmonberry) adjacent to the Rubus parviflorus.  We’re expecting lots of critters to find homes in and around the Thimbleberry and Salmonberry soon!

Parting Thought:  This post begins by noting that we planted the woodland garden under a canopy of oaks.  That may, at first, seem incompatible (particularly with moisture loving Rubus and dry-loving Oaks).  Rest assured, the topography and layout of the knoll on which the woodland garden was planted is hydrologically separated and downslope of the Oaks and in a separate hydrozone.

Sources:

The Jepson Manual, Vascular Plants of California, 2nd Edition, edited by Bruce G. Baldwin et al.

Flora of North America:  http://floranorthamerica.org/ 

Missouri Botanical Garden, Tropicos:  http://www.tropicos.org/Home.aspx

USDA Plant Database: http://plants.usda.gov/java/

California Native Plant Society:  http://www.cnps.org/

Las Pilitas Nursery:  http://www.laspilitas.com/

California Native Plants for the Garden, Carol Bornstein, David Fross and Bart O’Brien, Cachuma Press

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