Abietineae sentence example
- It has no Magnoliaceae, no maples, Pomaceae, or Vacciniaceae, no Rhododendros and no Abietineae.
- The spruce bears the smoke of great cities better than most of the Abietineae; but in suburban localities after a certain age it soon loses its healthy appearance, and is apt to be affected with blight (Eriosoma), though not so much as the Scotch fir and most of the pines.
- The female flowers of the Abietineae may be taken as representing a common type.
- Smaller cones, less than an inch long, occur in the larch, Athrotaxis (Tasmania), Fitsroya (Patagonia and Tasmania), &c. In the Taxodieae and Araucarieae the cones are similar in appearance to those of the Abietineae, but they differ in the fact that the scales appear to be single, even in the young condition; each cone-scale in a genus of the Taxodiinae (Sequoia, &c.) bears several seeds, while in the Araucariinae (Araucaria and Agathis) each scale has one seed.
- These projections and ridges may be homologous with the seminiferous scale of the pines, firs, cedars, &c. The simplest interpretation of the cone of the Abietineae is that which regards it as a flower consisting of an axis bearing several open carpels, which in the adult cone may be very small or large and prominent, the scale bearing the ovules being regarded as a placental outgrowth from the flat and open carpel.Advertisement
- It may be that the interpretation of the female cone of the Abietineae as an inflorescence, which finds favour with many botanists, cannot be applied to the cones of Agathis and Araucaria.
- Without expressing any decided opinion as to the morphology of the double cone-scale of the Abietineae, preference may be felt in favour of regarding the cone-scale of the Araucarieae as a simple carpellary leaf bearing a single ovule.
- In the Abietineae cell-formation in the pollen-grain is carried farther.
- It is held by some botanists (Celakovsky) that the seminiferous scale of the Abietineae is homologous with the arillus or second integument of the Taxaceae, but this view is too strained to gain general acceptance.
- In the Abietineae the cells of the middle tier elongate and push the lowest tier deeper into the endosperm; the cells of the bottom tier may remain in lateral contact and produce together one embryo, or they may separate (Pinus, Juniperus, &c.) and form four potential embryos.Advertisement
- A striking feature in the roots of several genera, excluding the Abietineae, is the occurrence of thick and somewhat irregular bands ofthickening on the cell-walls of the cortical layer next to the endodermis.
- In the Abietineae the phloem consists of parenchyma and sieve-tubes only, but in most other forms tangential rows of fibres occur in regular alternation with the parenchyma and sieve-tubes.
- A flower of a rather different type, Pseudaraucaria major, exhibiting in the occurrence of two seeds in each scale an approach to the cones of Abietineae, has been described by Professor Fliche from Lower Cretaceous rocks of Argonne.
- The Abietineae do not appear to have played a prominent part before the Wealden period; various older species, e.g.
- The Coniferae include no fewer than 94 species of Cupressineae and 17 of Abietineae, including several species of Sequoia.Advertisement