Glossary of terms used in cycad systematics - Cycad Specialist Group

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Walters & Osborne – Cycad Classification: Concepts & Recommendations, Appendix 2 16 paratype, para. Herbarium specimen cited in a description together with the holotype and any isotypes. See also lectotype, neotype. parenchyma. Thin-walled cells in storage tissues such as the cortex zone between the epidermis and vascular tissue. The starch-rich stems of Stangeria eriopus and similar cycads are mainly parenchymatous. paripinnate. Even-pinnate; of a leaf or leaflet where the rachis or rachilla does not terminate in a solitary pinna or pinnule. Cf. imparipinnate. PCR. Polymerase Chain Reaction, a technique for duplicating a small amount of DNA into a large number of DNA fragments of identical sequence, selectively controlled by a chosen DNA primer. See also RAPD. pectinate. Comb-like; with closely-spaced, narrow segments, as in the megasporophyll of Cycas pectinata. pedicel. Supporting stalk of a flower or gymnosperm sporophyll. See also peduncle. peduncle. Supporting stalk of an inflorescence or gymnosperm cone. See also pedicel. peltate. With a stalk positioned centrally on the surface of a lamina or sporophyll, as for most cycad bullae. pendent, pendulous. Hanging downwards, as for the female cones of many Dioon species. petiole. Stalk of a leaf; in a compound leaf, that part of the axis below the lowermost leaflets, pinnacanths or spines. See also rachis. petiolule. Stalk of a leaflet, that part of the axis below the leaflet blade, as seen clearly in Zamia manicata. See also rachilla. phenetic. Condition of an overall similarity of chosen characters between taxa but without regard to whether the characters are derived or due to convergence. See also Adansonian. phenology. In plants, the study of recurrent phenomena, such as episodes of reproduction, in relation to seasonal patterns. phenogram. Tree diagram showing taxa arranged hierarchically on the basis of phenotypic similarities without any regard for ancestry. See also cladogram, dendrogram, phylogram. phenotype. Sum total of morphological or other characters defining an organism or group. Cf. genotype. pheromone. Volatile chemical substance emitted by an organ and acting as a signal to other organisms, as in cycad cone emissions attracting insect pollinators. photosynthesis. Fundamental process in biosynthesis, by which carbon dioxide and water are converted to simple sugars using sunlight as an energy source. See also chlorophyll. phylogram, phylogenetic tree. Cladogram where branch lengths are proportional to the number of changes that occur at each branch. See also dendrogram, phenogram.
Walters & Osborne – Cycad Classification: Concepts & Recommendations, Appendix 2 17 phylogeny. Evolutionary history of an organism or group. physiographic. Relating to physical geography. physiology. Study of the functioning of organisms and their parts. phytochemistry. Study of plant chemistry, particularly in relation to secondary metabolites. phytogeography. Study of plants and their distribution in relation to geographic factors. pilose. With soft hairs. See also lanate, hirsute, pubescent, sericeous, tomentose. pinna, plural pinnae. Primary division of a compound leaf; leaflet. pinnacanth. Sharply-pointed structure intermediate between a leaflet and a spine, usually green and hence photosynthetic, as seen in on the rachises of some species of Dioon, Encephalartos and Macrozamia. See also prickle, tooth. pinnate. Feather-shaped; typically a leaf with leaflets or pinnae on either side of a rachis. See also bipinnate, multipinnate, pinnule. pinnule. Secondary division of a compound leaf. See also pinna. planche. French term used in some of the older botanical literature to denote illustrative plate. See also tabula. platyspermic. Of seeds, flattened so as to be not radially symmetrical, as in Cycas seeds. See also actinomorphic, zygomorphic. Cf. radiospermic. plesiomorphy. Ancestral or underived character or character state. Note that a plesiomorphy at a given hierarchical level may be an apomorphy at a more inclusive level. See also autapomorphy, homology, symplesiomorphy, synapomorphy. plicate. Pleated or folded longitudinally to give as corrugated appearance, as for the leaflet surface of Zamia roezlii. plumose. Feathery in a whorled appearance. pollen. Fine powdery material (microspores) shed from the microsporangia of seed plants; in cycads sometimes referred to as prepollen; microspores containing a male gametophyte (microgametophyte). pollen cone/strobilus. Male cone; microsporangiate strobilus. pollination. Transfer of pollen towards ovules. See also anemophily, entomophily. polymorphic. Persistently variable in form, as for populations of Macrozamia polymorpha and Zamia polymorpha. See also dimorphic, homomorphic, monomorphic. polyphyletic. Of an artifical group comprising members that have originated independently from more than one ancestor. See also monophyletic, paraphyletic. polythetic. Referring to a group sharing many, but not all, features. See also monothetic.
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Glossary of terms used in cycad systematics - Cycad Specialist Group

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