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Principles of Plant Biology

David R. Hershey dh321 at excite.com
Mon Nov 29 21:02:42 EST 2004

The American Society of Plant Biologists twelve Principles of Plant 
Biology are very worthwhile but I think twelve is too few. Here's a 
draft of what I would add for a second twelve. Any other suggestions?

13.  Plants are the dominant land organisms on a mass basis. "The mass 
of vegetation on the Earth very far exceeds that of animal organisms; 
for what is the volume of all the large living Ceteacea and Pachydermata 
when compared with the thickly-crowded colossal trunks of trees, of from 
eight to twelve feet in diameter, which fill the vast forests covering 
the tropical region of South America …?"

Alexander von Humboldt 1858

14. Plants often clone themselves, both vegetatively and by 
self-pollination followed by self-fertilization to produce seeds. For 
example, the pea cultivars Gregor Mendel started with were basically 
self-pollinating clones.

15. Plants adapt to diverse environments partly because they have 
tremendous phenotypic plasticity. For example, an old tree on nutrient 
poor soil or in a harsh environment may be 5% or less the height of a 
tree of the same species and age in a better environment.

16. Plants have tremendous diversity in habit (trees, shrubs, herbs, 
bulbs, vines, epiphytes, aquatics, succulents, etc.).

17. Some plants have incredible longevity. For example, bristlecone 
pines can approach 5,000 years old, a King's holly shrub is about 43,000 
years old and the 'Pando' quaking aspen clone may be over a million 
years old.

18.  Not all plants are photosynthetic. Over 300 species are parasitic 
and therefore heterotrophic, including important weeds such as dodder 
and broomrape, and the world's largest flower Rafflesia.

19. Plants have coevolved with many organisms, including mycorrhizal 
fungi, nitrogen-fixing bacteria, ant protectors, animal pollinators 
animal seed dispersers and most recently humans.

20. Plants have many important roles in society including as symbols, 
memorials, toys, gifts, decorations, tourist attractions, state trees, 
state flowers and in art, architecture, humor, literature, poetry and 
religion. Plants also often appear on coins, currency, stamps and flags.

21. Plants have played an important role in human history such as the 
economic collapse in early 1600's Holland due to speculation in tulip 
bulbs and Columbus's search for spices that resulted in the discovery of 

22. People have severely damaged natural plant populations by 
introducing thousands of foreign plants, animals and microbes that have 
decimated native plant populations. For example, the American chestnut 
was virtually wiped out by an introduced fungus.

23. Without plants, our outdoor environments would be barren and harsh. 
Landscape plants enhance our environmental quality by providing shade 
and beauty, moderating temperatures, screening unsightly views, 
preventing erosion and reducing windspeed.

24. Plants have long been neglected and discriminated against in biology 
teaching, which has caused an epidemic of plant illiteracy and numerous 
widespread plant misconceptions.

David R. Hershey
dh321 at excite.com

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