Addition à la flore du Guatemala: Vanilla esquipulensis (Orchidaceae), espèce des forêts xérophytes.
Much of my work also involves the development of new tools or ways of knowing.
Philip Sandford Boone Chair in Paleontology, Director of the University of California Museum of Paleontology (UCMP); Chair of the Berkeley Natural History Museums (BNHMs); co-Director of the Berkeley Initiative in Global Change Biology (Bi GCB); Joint appointment in Earth and Planetary Sciences.
I am broadly interested in how paleontology can inform our understanding of the history of life, and the processes that control it.
Pirani & Prado Gametophyte dominant, independent, multicellular, not motile, initially ±globular; showing gravitropism; acquisition of phenylalanine lysase [PAL], microbial terpene synthase-like genes , triterpenoids produced by CYP716 enzymes, phenylpropanoid metabolism [lignans , flavonoids (absorbtion of UV radiation)], xyloglucans in primary cell wall, side chains charged; plant poikilohydrous [protoplasm dessication tolerant], ectohydrous [free water outside plant physiologically important]; thalloid, leafy, with single-celled apical meristem, tissues little differentiated, rhizoids , unicellular; chloroplasts several per cell, pyrenoids 0; glycolate metabolism in leaf peroxisomes [glyoxysomes]; centrioles/centrosomes in vegetative cells 0, microtubules with γ-tubulin along their lengths [? For the diversity of pollen presentation devices in the family, see Erbar and Leins (1988) and Leins and Erbar (2003b, 2010).
here], interphase microtubules form hoop-like system; metaphase spindle anastral, predictive preprophase band [with microtubules and F-actin; where new cell wall will form], phragmoplast [cell wall deposition centrifugal, from around the anaphase spindle], plasmodesmata ; antheridia and archegonia jacketed, surficial; blepharoplast , centrioles develop de novo, bicentriole pair coaxial, separate at midpoint, centrioles rotate, associated with basal bodies of cilia, multilayered structure [4 layers: L1, L4, tubules; L2, L3, short vertical lamellae] (0), spline [tubules from L1 encircling spermatid], basal body 200-250 nm long, associated with amorphous electron-dense material, microtubules in basal end lacking symmetry, stellate array of filaments in transition zone extended, axonemal cap 0 [microtubules disorganized at apex of cilium]; male gametes [spermatozoids] with a left-handed coil, cilia 2, lateral; oogamy; sporophyte multicellular, cuticle , plane of first cell division transverse [with respect to long axis of archegonium/embryo sac], sporangium and upper part of seta developing from epibasal cell [towards the archegonial neck, exoscopic], with at least transient apical cell [? In nearly all species the pollen is initially enclosed by the indusium, and is pushed out by the elongating style; the pollen of Brunonia, with its capitate inflorescence and flowers with straight styles, is held in a brush formed by stylar hairs.