Month: September 2022

GENES AND FUSION. "Boundary formation gene regulatory network (GRN) and fusion of floral organs. (a) A floral diagram with four concentric whorls showing different planes along which fusion (or lack of separation) of floral organs typically occurs." (See Fig 2). https://lnkd.in/dD4GcAS View in LinkedIn

TYPES OF FLOWER FUSIONS. "(1) Connation of sepals, resulting in a calyx tube; (2) adnation of sepals and petals; (3) connation of petals; (4) adnation of petals and stamen; (5) connation of stamens to form a staminodial tube; (6) connation of carpels leading to a syncarpous gynoecium." https://lnkd.in/dD4GcAS View in LinkedIn

FUSION OF DISSIMILARS. "Fusion of stamen, petals and carpels into a single floral tube also appears throughout angiosperm evolution and appears to be mediated by different mechanisms that either stamen–stamen or carpel–carpel fusion." https://lnkd.in/dD4GcAS View in LinkedIn

TIMING OF FUSIONS. "Fusion as a developmental process can occur early or late during the development of an organ series (congenital fusion), or can occur at the margins of fully formed organs (postgenital fusion). Within the congenital fusion spectrum, fusion of the developing primordia can occur early or late during organogenesis." https://lnkd.in/dD4GcAS View in LinkedIn

TIMING OUTCOMES. "Late fusion occurs when the primordia appear as distinct early on but the individual organs eventually fuse during development, often at the base, leaving the tips of the primordia free (usually found in asterids). By contrast, early fusion occurs when the fused organs appear first as a ring meristem or fascicle on which individual organ primordia appear later (usually found in rosids); thus, the base of the organs are fused from inception." https://lnkd.in/dD4GcAS View in LinkedIn

PETAL FUSIONS. "Fusion of the petals (sympetaly) characterizes the asterids and especially the euasterids, but also occurs independently in some monocots, early diverging eudicots (e.g. some Ranunculaceae) and core eudicots (e.g. Malvaceae, Rosaceae)." https://lnkd.in/dD4GcAS View in LinkedIn

TWO PROCESSES. "Sympetaly itself involves the combination of two developmental processes: meristem fusion of petal primordia; and the establishment of an intercalary meristem that produces a floral tube via intercalary elongation. Perianth synorganization can include fusion of petals alone, or can unite the petals with the stamens into a floral tube, resulting in concerted evolution of floral form." https://lnkd.in/dD4GcAS View in LinkedIn

FUSION FUNCTIONS. "Functionally, the fusion of perianth organs can offer protection in bud as well as promoting specific associations to enhance pollination. Fusion of stamens and petals may also present opportunities for the emergence of elaborations on petals and staminodes that play a major role in nectar production and canalization for purposes of effective pollination." https://lnkd.in/dD4GcAS View in LinkedIn

NEW STRUCTURES. "Finally, fusion events within the canonical perianth whorls may result in the formation of novel boundary regions, resulting in additional floral whorls; the corona, a novel organ that forms between the perianth and the androecium, is prominent in several monocot and core eudicot lineages as a result of novel boundary generation between the petal and stamen whorls." https://lnkd.in/dD4GcAS View in LinkedIn

SO ENDS this dalliance into flower structure, which will conclude next weekend. Flowers are complex both developmentally and from an evolutionary viewpoint. But a small set of parts, by virtue of fusion and non-fusion, can generate a wide range of floral complexity. That simplicity can beget complexity is true across nature, from amino acids and proteins, the limited pallet of the elements, to crystal types. In all cases, a small starting set generates remarkable diversity of form. View in LinkedIn