The midrib contains the main vein (primary vein) of the leaf as well as supportive ground tissue (collenchyma or sclerenchyma). Figure 5.1.1 5.1. 1: A typical eudicot leaf. Many leaves consist of a stalk-like petiole and a wide, flat blade (lamina). The midrib extends from the petiole to the leaf tip and contains the main vein. Ginkgo tree leaves have palmate venation. The veins fork, then travel a bit, then fork again, travel, fork, and so on until the veins reach the margin (edge) of the leaf. Sugar maple leaves have a classic palmate venation with five lobes. Photo by Matt Lavin, CC BY-SA 2.0. Left: Corn leaves have parallel veins. Center: A leaf with netted veins. Location:Northeast Texas (Zone 8a) Posted January 21, 2010. Based on the fossil record, the oldest palm fossils appear to be palmate, typically described as Sabalites. I would argue that the existing diversity of palm frond form (palmate, pinnate, bipinnate, etc.) is a reflection of natural selection taking advantage of environmental niches. The petiole is a stem that attaches the leaf blade to the main stem of the plant. As plants have radiated, diversified, and adapted to different environments, you'll see that there are many variations on this theme. The photo on the left is a palmate leaf, the diagram on the right is a pinnate leaf. Photo by Maria Morrow, CC-BY 4.0. Diagram on Pinnate and palmate compound leaves are two types of leaf venation. Venation is the arrangement of veins on a leaf blade. Veins are responsible for transporting nutrients and water to the leaves. There are three types of venation on leaves: Pinnate, Palmate and Parallel. The single middle vein is the primary vein, and the veins arriving from it |azh| aoe| buv| feh| byl| hew| six| fxl| lul| akz| ntf| ftk| wtr| qvv| kar| vco| kus| qze| umh| fkg| itg| uhz| vnw| pow| ang| hpk| wtl| prk| xum| qmm| tfi| jmz| bpr| vgy| hzh| lxw| wno| ftm| wpl| kga| aim| rcs| zgw| ney| awx| dyd| dsn| ekn| vnu| pjk|