Because of the harsh conditions, most alpine plants are small ground-hugging perennials that grow and reproduce slowly. Many form tight buns of rosettes which help shelter the plant's crown and leaves. Soils are generally poor because organic matter decomposes very slowly in extreme cold and drainage is very sharp. These are not desert plants for the most part because they receive copious early season water as the snow and ice melt. Many are constantly supplied with cold, running water at root level. None of them, however, will put up with soggy conditions around their crowns nor hot, humid weather.
One extreme example of alpine ground-hugging ability is Raoulia australis , the vegetable sheep, whose minute, succulent, gray leaves form a tight fitting mat on rocks in New Zealand and Australia, often reaching only one half inch tall (1.2 cm).
Not all alpines are tiny plants, however, the endangered native Hawaiian Haleakala silversword ( Argyroxiphium sandwicense), a member of the aster family (Asteraceae), after twenty years as a ground-hugging porcupine, sends up a tall
flowering stalk from its tight bun of silver foliage. Once it flowers, it dies. Endemic to volcanic mountain slopes, it is nearly extinct and now on the protected list.
Hydrophytes
At the opposite end of the environmental spectrum are the hydrophytes; water plants, like the water lilies (Nymphaea spp. ) pictured, who require lots of water and may live wholly or partially submerged in water all their lives.
In general, their leaves will be broad and thin with thin cuticles and stomata located on the upper surface. They have large air spaces between cells, which, in the case of floating leaves like water lilies, helps them stay above water. Their veins help provide form and keep them floating. The most extreme of these is the giant Amazon water lily, Victoria amazonica, whose structure will support a small adult or a couple of children.
Mesophytes
"Middle" plants are those found in moderate habitats. Compared to dry land plants, they have wider and thinner leaves whose stomata can be located on both upper and lower surfaces. They don't have special modifications for climate, which makes the reason why their leaf shapes differ harder to pinpoint...especially why the same plant produces markedly different leaf shapes.
Since these are the plants found in most temperate regions, including my USDA zone 7 Maryland garden, it is they who have spurred me on in my quest for the answers to these questions that will be revealed in my next article. See ya' later!
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