This variation, arising due to several factors, offers great functional significance that influences plant success. But their attractiveness lies in their varying shapes and sizes from the uncommon butterfly-shaped leaf of Christia obcordata to the extensively studied ovate-shaped leaf of Arabidopsis thaliana (Figure 1A and B). In comparison to the vibrant colors of the flower, the ‘leaf’ has nothing special to offer as most are green-colored attributed to the presence of chlorophyll. In hindsight, formation of the pitcher tube in Nepenthes might involve the recruitment of similar genetic mechanisms that occur during sympetaly in Petunia. the pitchers of the carnivorous plant Nepenthes which have evolved to provide additional support to the plant survival in its nutrient-deficient habitat. This immense amount of information available will serve as the basis for studying and understanding innovative leaf morphologies viz. ![]() In addition to genetic control, environmental factors also play an important role during the final adjustment of leaf shape. We found that the underlying factors governing these processes are inherently genetic: PIN1 and KNOX1 are indicators of leaf initiation, HD-ZIPIII, KANADI, and YABBY specify leaf outgrowth while ANGUSTIFOLIA3 and GROWTH-REGULATING FACTOR5 control leaf expansion and maturation besides, recent research has identified new players such as APUM23, known to specify leaf polarity. Here, we review these studies and discuss the various factors that contributed towards shaping the leaf initiated as a small bulge on the periphery of the shoot apical meristem (SAM) followed by asymmetric outgrowth, expansion and maturation until final shape is achieved. This has fascinated scientists worldwide, and research has progressed tremendously in understanding the concept of leaf shape determination. During the course of evolution, the megaphylls have attained complexity not only in size or venation patterns but also in shape. Significant contributions have come from megaphyllous leaves, characterized usually as flat, thin lamina entrenched with photosynthetic organelles and stomata, which serve as the basis of primary productivity. Golden ragwort is in the Asteraceae, and is by far the earliest blooming native of that family (in this region, anyway).The independent origin and evolution of leaves as small, simple microphylls or larger, more complex megaphylls in plants has shaped and influenced the natural composition of the environment. Garlic mustard is in the Brassicaceae, a family which also includes several of our native spring ephemerals, like the toothworts and rockcresses. By the time the plants reach this stage, they are easy to tell apart. Look at how different it is from the stem leaves of garlic mustard, which look similar to the basal leaves. Also in this photo you can see the flower buds at top. <- This is a stem leaf of golden ragwort. The leaf venation is also pinnate, but also netted, giving the leaf a bit of a crinkled appearance. The leaf edges are clearly scalloped rather than toothed. The underside of the leaf has a purplish blush. Note that the leaf edges are somewhat crenate (scalloped), almost serrate, and that the leaf vein pattern is pinnate. Luckily, I was able to find both growing right next to each other! ![]() When young, they are easily confused with each other, at least at first glance. ![]() I was thinking recently about two other species with similar cordate basal leaves. Or like these, which belong to wild ginger ( Asarum canadense). Like the violets in my last post, for example. At this time of year many plants are putting out – or have already have put out – heart-shaped leaves that stay close to the ground.
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