. Comparative anatomy of the vegetative organs of the phanerogams and ferns;. Plant anatomy; Ferns. 238 PRIMARY ARRANGEMENT OF bundles. Sometimes only one marginal bundle unites with the median, sometimes neither. These 3, 4 or 5 bundles of a trace rarely run unaltered through the stem: the appearanqe of a trace is varied by occasional splittings and reunions, so that it may retain 3-5 bundles (with a width of ^th to ^th of the circumference of the stem), or be re- duced to 2 or I bundle. The leaf-trace may be followed through 6-8 internodes, but further down it is impossible to reco
. Comparative anatomy of the vegetative organs of the phanerogams and ferns;. Plant anatomy; Ferns. 238 PRIMARY ARRANGEMENT OF bundles. Sometimes only one marginal bundle unites with the median, sometimes neither. These 3, 4 or 5 bundles of a trace rarely run unaltered through the stem: the appearanqe of a trace is varied by occasional splittings and reunions, so that it may retain 3-5 bundles (with a width of ^th to ^th of the circumference of the stem), or be re- duced to 2 or I bundle. The leaf-trace may be followed through 6-8 internodes, but further down it is impossible to recognise with certainty how many bundles belong to each leaf. Within the first 5 internodes no crossing or uniting with lower leaf-traces has been observed. To this type belong Impatiens Bahamina and Scopolina atropoides (Nageli). 3. Leaves spirally arranged. Leaf-trace of five bundles, pectinating with the third or fifth. Cocculus laurifoliui (Nageli). 4. Leaves spirally arranged. Leaf-trace of three bundles which pectinate with the second and third. Lupinus Lehnianni, Hort, and L. luteus, L. (Figs. 94, 95). In the seedling a pair of opposite primordial leaves, or first foliage leaves alternates with the two cotyledons. The second pair of foliage leaves, of which one is inserted rather lower and develops earlier than the other, alternate with the above, and are thus opposite the cotyledons. The two leaves of the third pair are not only at an unequal height, but also show a distinct horizontal deviation from the opposite arrangement. The fourth pair is intermediate between an opposite and spiral ar- rangement ; all later leaves are arranged in a spiral. Each cotyledon has a leaf-trace of two bundles {a, b), which become united into one in the lower portion of the hypocoty- ledonary stem. Sometimes there is found a third weaker bundle between the two bundles of one cotyledon. All later leaves have three bundles. Those of the primordial leaves, which will be called III and IV (e, d,
Size: 917px × 2727px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecad, booksubjectplantanatomy, bookyear1884
