Month: September 2022

TWO LINEAGES. "Plants evolved leaves on at least two independent occasions and the legacy of these historic evolutionary events is represented in extant floras by microphylls in lycophytes (clubmosses, spikemosses and quillworts) and megaphylls in euphyllophytes (ferns, gymnosperms and angiosperms)." http://aob.oxfordjournals.org/content/96/3/345.full.pdf View in LinkedIn

FLAT BIG LEAVES. "The vast majority of the estimated 250 000 or so extant species of flowering plants, as well as most gymnosperms and (extinct) pteridosperms, utilize(d) a flat-bladed megaphyll with a network of veins to capture solar energy for photosynthetic carbon assimilation." http://aob.oxfordjournals.org/content/96/3/345.full.pdf View in LinkedIn

GIANT IMPACT. "Megaphylls altered the evolutionary trajectory of terrestrial plant and animal life, the biogeo-chemical cycling of nutrients, water and carbon dioxide and the exchange of energy between the land surface and the atmosphere." http://aob.oxfordjournals.org/content/96/3/345.full.pdf View in LinkedIn

PRIMARY SOURCE OF ENERGY. "A true measure of their success in terrestrial environments is the capacity of leaves to endure climatic extremes between the tropics and the tundra whilst simultaneously facilitating the global scale net fixation of approx. 207 billion tonnes of CO2, 56.4 x 10(15) g C year(-1). This primary production provides energy for virtually all forms of terrestrial life on Earth, especially tetrapods and insects, and links many ecosystem and biogeochemical processes." http://aob.oxfordjournals.org/content/96/3/345.full.pdf View in LinkedIn

FRAGMENT FROM NATURE continues from last weekend and concludes this weekend on the theme of the plant leaf. Few structures have so exemplified life on Earth, nor caused such massive changes as plant leaves, from the vast grasslands to the dense forests. And the more we learn, the more sentient and knowing image of plants have emerged, departing from a stereotype of insensate dumb vegetation. Revisit your smart planetary neighbor with fresh eyes. View in LinkedIn

GLOBAL SUCCESS. "Evidently, leaves are a global success. However, the advent of large megaphylls took place some 40–50 million years (Myr) after the origination of vascular land plants, suggesting that they were far from an evolutionary inevitability." http://aob.oxfordjournals.org/content/96/3/345.full.pdf View in LinkedIn

FIRST PLANTS WERE LEAFLESS. "The earliest ancestral vascular plants, dating to the late Silurian 410 Myr ago, were composed of simple or branched axial stems with sporangia but no leaves." http://aob.oxfordjournals.org/content/96/3/345.full.pdf View in LinkedIn

LATE ARRIVAL OF LEAFED PLANTS. "Surprisingly, plants continued to remain leafless for the next 40–50Myr, with megaphylls finally becoming widespread at the close of the Devonian period (360 Myr ago)." http://aob.oxfordjournals.org/content/96/3/345.full.pdf View in LinkedIn

FIRST SURPRISE. "Surprise in the delayed appearance of a seemingly simple developmental modification is 3-fold. First, palaeontological evidence shows that the structural framework necessary for assembling a simple laminated leaf blade (meristem, vasculature, cuticle and epidermis) was in place long before the advent of large megaphylls." http://aob.oxfordjournals.org/content/96/3/345.full.pdf View in LinkedIn

SECOND SURPRISE. "Secondly, the same interval marks an unparalleled burst of evolutionary innovation in the history of plant life, which witnessed the rise of trees from herbaceous ancestors, and the evolution of complex life cycles, including the seed habit." http://aob.oxfordjournals.org/content/96/3/345.full.pdf View in LinkedIn