Why not fire truck berries?

In the fall, many plants in western Oregon (and elsewhere) produce brightly-colored fruits. These attract fruit-eating animals, which eat the fruits and move their seeds to new locations, potentially better sites for germination and survival. By and large, such fruits are red, blue, or purple – colors that contrast with surrounding vegetation and appeal to birds, but snowberries (Symphoricarpos albus) buck the trend, producing white fruits about the size of huckleberries that dangle on the ends of flimsy stems.

Snowberry (Symphoricarpos albus), a shrub with unique, white fruits.

Snowberry (Symphoricarpos albus), a shrub with unique, white fruits.

Why are snowberries white when so many other plants produce red berries? If the red of other fruits has been selected to enhance seed dispersal by birds, maybe the white of snowberry has been selected for dispersal by another agent. In the tropics, white or green fruits are commonly eaten by bats. Flying through a dark forest, a bat may detect a white fruit more easily than a red one, particularly if it has a strong odor and is hanging at the end of a long branch. Unfortunately, there are no tropical fruit bats in western Oregon*, but there are nocturnal fruit-eaters. Perhaps woodrats or flying squirrels cue in on snowberries.

Alternatively, snowberries might be white because why not? Presumably red fruit pigmentation exacts some energetic toll from plants, so all else being equal, a white fruit should cost less than a red one. Pheasants and turkeys appear content to eat unadorned snowberries, and some of their seeds are able to germinate following gut passage**. Selection on snowberry’s dispersal mechanism may also be weaker than for other plants; S. albus seems to reproduce more commonly via spreading rhizomes than from seeds.

 

*Though a vampire bat in the same family existed in northern California during the Pleistocene.

**Based on the results of a seed viability study from turkey feces conducted by Sara Evans-Peters at OSU.

More snowberries

How did this snowberry get to Jackson-Frazier Wetland?

A more common

Rose hips: targeted advertising for visually-oriented consumers.

 

Advertisements

About Leighton Reid

Restoration Ecologist
This entry was posted in Ecology and tagged , , , , . Bookmark the permalink.

3 Responses to Why not fire truck berries?

  1. Interesting question. Parallel to the question of whiteness in flowers. Here in TN, the earliest flowers are white, then purples and other colors come into play. I’ve assumed (with zero data) that this is related to the changing light environment as the trees leaf out. Are snowberries found in particularly open areas where full spectrum reflectance would be particularly conspicuous?

    Poison Ivy berries are also kinda white. The best white berry of them all: baneberry (Actaea pachypoda). Crazy white, with freaky red stalks. Dispersed by gnomes and fairies.

    • I have mostly seen snowberries in edge habitat. In the wetlands near my home they grow right alongside bright red rose hips. I first noticed the berries along the trail about the same time that the trees in the wetland lost all of their leaves, so maybe you are onto something with the changing light environment.
      Indeed, poison ivy berries are greenish-white, but they’ve also got those nice red leaves in the fall that could serve as visual cues. It would be interesting to dye some snowberries and see if removal rates changed.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s