The families of gymnosperms
Plum Yew, Cows Tail Pine.
Vegetative. Evergreen; small trees and shrubs. Resinous (with resin canals in stem pith and cortex, and in the leaves). Main branches whorled, or opposite. The leafy branchlets flattened in one plane. The vegetative branch systems without conspicuously specialised short-shoots. Mature leaves linear; relatively soft; not clustered; alternate. Longitudinal resin canals present in the leaves; 1 per leaf, this median-abaxial.
Reproductive organization. Usually dioecious. The ovules borne in female cones (the young cone comprising a thick, rather fleshy axis bearing a few bracts, each bract subtending a pair of transversely placed ovules of which only one or two per cone mature to produce olive-like seeds). The seed-cone scales opposite and decussate; persistent. The ovules ostensibly axillary (in pairs, though arguably each pair terminates an extremely abbreviated short-shoot, with the latter then seen as representing the ovuliferous scale of other coniferous cones); paired, orthotropus; 1 integumented (this fused with the nucellus except at its apex).
The male cones with spirally arranged microsporophylls. Prothallial cells lacking. Pollen-sacs (2–)3 per microsporophyll. Pollen without air bladders. Pollination anemophilous, involving a liquid drop mechanism.
Seeds and seedlings. Seeds with a fleshy investment; the fleshy investment developed from the integument; wingless. Cotyledons 2.
Wood anatomy. Growth rings indistict. Heartwood present but not distinctively coloured, or absent. Latewood not conspicuous. Wood without distinct odour; without distinct taste; not greasy; without dimpled grain. Tracheids with neither alternate nor opposite bordered pits; without callitroid pit-border thickenings. Margins of the tori not scalloped. Earlywood tracheids with spiral thickenings. Axial parenchyma present. Axial parenchyma abundant. Axial parenchyma not zonate. Axial parenchyma with nodular thickenings or bead-like on the transverse or end-walls. Ray tracheids absent or very infrequent. Earlywood ray cells with walls similar in thickness to those of adjacent vertical tracheids. Latewood ray cells with pitted horizontal walls. The pitting weak. Ray cells exhibiting indentures at the corners; without nodular thickenings on their end walls. Ray tissue without crystals. Earlywood cross-field pits piceoid. Normal vertical resin ducts absent.
Geography, cytology. Eastern Himalayas to Japan.
Basic chomosome number, n = 12.
Taxonomy. 4 species; Cephalotaxus. Order Coniferales, or Taxales (? - assignment disputed).
Miscellaneous. • Cephalotaxus harringtonia var. drupacea and Cephalotaxus fortunei (Dallimore and Jackson). • Cephalotaxus species: female shoot and cone details (various sources). • Leaf epidermis: Cephalotaxus fortunei (Florin). • Cephalotaxus drupacea (Chittenden).
To view the illustrations with detailed captions, go to the interactive key. This also offers full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2008 onwards. The families of gymnosperms. Version: 9th April 2015. delta-intkey.com’.