Title

Fruit morphology and terminal velocity in Tragopogon dubius

Document Type

Journal article

Source Publication

Functional Ecology

Publication Date

1989

Volume

3

Issue

2

First Page

489

Last Page

496

Publisher

Wiley-Blackwell Publishing Ltd.

Abstract

In a manipulative experiment the following predictions about the relationship between fruit mass, pappus area, and terminal velocity in the fruits of Tragopogon dubious (L.) were tested: (1) terminal velocity should be proportional to the square root of disk loading (disk loading = mass/area), (2) when pappus area is held constant, terminal velocity should be proportional to the square root of the mass and (3) when fruit mass is held constant, terminal velocity should be inversely proportional to the square root of pappus area. Although qualitative support was found for each prediction, terminal velocity declined more slowly than predicted with increasing pappus area and increased more quickly than expected when mass was increased. When disk loading was held constant, fruits with larger pappuses fell more quickly than fruits with smaller pappuses. These results suggest that the area of the pappus is not a good estimator of its ability to produce drag (its effective area) for two reasons: (1) because the radial morphology of the pappus causes the density of drag producing cross hairs to decrease along the length of the pappus ray and (2) because the projected area of the pappus may change if the pappus is bent upwards by the drag force acting on it. Thus, increasing parental investment in pappuses does not decrease terminal velocity as quickly as expected.

DOI

10.2307/2389623

Print ISSN

02698463

E-ISSN

13652435

Publisher Statement

Copyright © 1989 Wiley-Blackwell Publishing Ltd. Access to external full text or publisher's version may require subscription.

Full-text Version

Publisher’s Version

Recommended Citation

McGinley, M. A., & Brigham, E. J. (1989). Fruit morphology and terminal velocity in Tragopogon dubius. Functional Ecology, 3(4), 489-496. doi: 10.2307/2389623