Meristem
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In cell biology, the meristem is a structure composed of specialized tissue found in plants, consisting of stem cells, known as meristematic cells, which are undifferentiated cells capable of continuo
Microscopic image of a shoot apical meristem surrounded by leaf primordia of Arabidopsis thaliana.
Note the long spur of the above flower. Spurs attract pollinators and confer pollinator specificity. (Flower: Linaria dalmatica)
Complex leaves of Cardamine hirsuta result from KNOX gene expression
The evolution of plants has resulted in a wide range of complexity, from the earliest algal mats of unicellular archaeplastids evolved through endosymbiosis, through multicellular marine and freshwate
The Devonian marks the beginning of extensive land colonization by plants, which – through their effects on erosion and sedimentation – brought about significant climatic change.
A banded tube from the Late Silurian/Early Devonian. The bands are difficult to see on this specimen, as an opaque carbonaceous coating conceals much of the tube. Bands are just visible in places on the left half of the image. Scale bar: 20 μm
The lycopod Isoetes bears microphylls (leaves with a single vascular trace).
The branching pattern of megaphyll veins may indicate their origin as webbed, dichotomising branches.