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"FLOWERS EVOLVED FOR SEX. We associate animals like bees, bats, and birds with flowers today but most of these lineages came much later in the game. Exactly what was around pollinating early flowers remains a bit of a mystery as well. Were the earliest flowers wind pollinated or was there some insect or even reptile that served the selection pressure necessary for their evolution? Only time and more fossil discoveries will tell." https://lnkd.in/euP3eDr View in LinkedIn

MASSIVE WATER FLUX. "The pulvinus is the organ responsible for the nyctinastic leaf movement. It is a specialized structure located at the base of the petiole of leaves or the petiolule of leaflets in the case of compound leaves. During leaf opening, leaflets move downward by the simultaneous increase of turgor pressure in extensor and decrease in flexor cells. During closing, the inverse occurs, extensor cells shrink, and flexor cells swell, moving leaflets upward. These turgor changes in the motor cells are caused by ion movements followed by massive water flux across the plasma membrane." https://lnkd.in/eE__XBs View in LinkedIn

VAST STRUCTURAL DIVERSITY. "Flowers, the reproductive organs of angiosperms, are more varied than the equivalent structures of any other group of organisms. Because of this variation, interest in plant sexual diversity has a long and venerable history in biology. However, despite this attention, it is still not obvious why flowering plants have evolved such extraordinarily diverse means to achieve only one primary function — mating success." https://lnkd.in/eSndawa View in LinkedIn

"THE PULVINUS is an enlarged motor organ at the base of leaves found in many leguminous plants. It has been observed to force the movement of leaves in heliotropic, seismonastic, and nyctinastic patterns." https://lnkd.in/e9s_fPH View in LinkedIn

ABOMINABLE MYSTERY. "Darwin called their sudden appearance in the fossil record an “abominable mystery.” Since Darwin's time, we have been able to clarify that picture a little bit. Even so, our understanding of the origin of the angiosperm lineage is dubious at best. When and why did flowers evolve? There is scant fossil evidence to illustrate the early evolutionary steps in this development of flowers." https://lnkd.in/euP3eDr View in LinkedIn

INITIATED BY DARWIN. "In his book entitled The Power of Movement in Plants, Darwin (1880) described many examples of “sleep movements of leaves” and provided a “List of Genera, including species the leaves of which sleep”. Among these, he noted that the legume family “includes many more genera with sleeping species than all the other families put together.” He also described a specialized organ, called a joint, cushion, or pulvinus responsible for such movement. https://lnkd.in/eE__XBs View in LinkedIn

"FLOWER OPENING depends on petal movements, of which at least four types can be distinguished. (1) Opening is due to reversible ion accumulation, and independent of elongation growth; (2) it depends on cellular death in a specific area of the petal; (3) it is due to loss of water during the day and refilling during the night; and (4) it depends on differential growth." https://lnkd.in/eTEzGE9 View in LinkedIn

ELEGANT ENGINEERING. "In some flowers, for example in Oenothera spp., the sepals are connected by a zipper‐like mechanism whereby cells at the sepal margins are tangled. Due to the force of the growing petals this entanglement is broken and the petals are suddenly released. In several other species the sepal margins are tightly held together by ridges, which also delay opening until the growing petals overcome their resistance. This also results in rapid opening." https://lnkd.in/eTEzGE9 View in LinkedIn

DIVERGENT SOLUTIONS. "Depending on the species, opening may relate to the development of tissues adjacent to the flower, for example, opening may require growth of the pedicel, as in several species in the Iridaceae; or it may require forced separation or abscission of covering parts, such as bracts or sepals." https://lnkd.in/eTEzGE9 View in LinkedIn

SO ENDS this first weekend fragment from nature on flower opening and closing. Flowering plants have the most diverse, curious, imaginative and wonderful sexual organs of all species on earth. The numerous advantages of sexual reproduction include purging poorly adapted genes, and these plants have expanded from purely clonal vegetative reproduction to become dominant species on planet earth. View in LinkedIn