Leaves - Shape Part 1
If you've ever grown plants from seed, you know that the seed leaves (cotyledons) seldom bear any resemblance to the plant's adult leaves.
Cotyledons are a form of modified leaf that are found on embryonic plants and generally serve as storage organs that feed the new born seedling until it has established enough of a root system to nourish itself.
The immature leaves of some plants are quite similar to the adult leaves, as those of the Germander illustrated...you can easily see the relationship; the young leaf just hasn't developed all the scallops at the edges.
But other plants are like a lot of creatures, including humans; the young leaves change considerably as they mature. These Pachysandra leaves clearly show the changes from youth to maturity.
Some plants have juvenile leaf forms their entire lives Pfitzer junipers (Juniperus chinensis 'Pfitzeriana') is one example.
Some, like Hedera helix retain juvenile leaf forms until they reach the top of their host and can climb no farther. They also have to be a certain age. I have read fifty years, but I know from my own ivies that maturity comes sooner; perhaps after twenty years. Juvenile and adult ivy leaves are very different. Even the narrowly cut forms broaden and lose almost all their indentations when mature.
I can well understand the differences between juvenile and mature leaves. This makes sense because most life forms have these kinds of changes. But why are there so many different leaf shapes in the first place? And, why do the leaves vary in shape on single species?
Continue the quest for the answers next time. See ya' later!
More Information
- For an in-depth list of descriptive terms for leaf shapes see the Brooklyn Botanic Garden's Leaves.
- If you aren't familiar with carnivorous plants, or even if you are and just love photos of fantastic plants, visit the Galleria Carnivora. If you're looking for extensive information about these plants, see The Carnivorous Plant FAQ.
- For additional illustrations of Leaf Margins.
Credits
All images are by Marge.
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The copyright of the article Leaves - Shape Part 1 in Shade Gardening is owned by Marge Talt. Permission to republish Leaves - Shape Part 1 in print or online must be granted by the author in writing.
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