Characteristics of the phloem

The anatomy of the bark of the Portulacaceae is also very heterogeneous. See legends to Figs. 8 and 9.

Fig. 5. Scalariform to reticulate inter-vessel pits. Thick vertical rhizome of a10 cm-high hemicryptophyte, meadow, alpine zone, Colorado, USA. Claytonia megarhiza, radial section.

Left Fig. 1. Biannual plant with two distinct rings. Root collar of a 20 cm-high prostrate hemicryptophyte, vineyard, hill zone, Switzerland. Portulaca oleracea, transverse section, polarized light.

Right Fig. 2. Diffuse-porous xylem. The ring boundary is defined by a few rows of radial flat parenchyma cells. Grey spots in vessels represent crystal druses. Root collar of a 20 cm-high prostrate hemicryptophyte, vineyard, hill zone, Switzerland. Portulaca oleracea, transverse section, polarized light.

Fig. 3. Semi-ring-porous xylem with distinct marginal parenchyma in the early-wood and the latewood. Vessels are arranged in radial rows. Fibers are fairly thick-walled. Root collar of a 20 cm-high dwarf shrub, on a rock, hyperarid, Athacama desert, Chile. Cistanthe salsoloides, transverse section.

Fig. 4. Simple structure of the rayless xylem and phloem. Vessels and parenchyma cells have almost the same diameter. The parenchyma seems to be pervasive. Thick vertical rhizome of a 10 cm-high hemicryptophyte, meadow, alpine zone, Colorado, USA. Claytonia megarhiza, transverse section.

Fig. 5. Scalariform to reticulate inter-vessel pits. Thick vertical rhizome of a10 cm-high hemicryptophyte, meadow, alpine zone, Colorado, USA. Claytonia megarhiza, radial section.

o o cry

250 Mm

Left Fig. 6. 1-3-seriate rays. Some uniseri-ate rays are unlignified (blue). Root collar of a 20 cm-high dwarf shrub, on rock, hyperarid, Athacama desert, Chile. Cistanthe salsoloides, tangential section.

Right Fig. 7. 4-8-seriate rays. The ray cells are partially irregularly formed and their walls are unlignified. Root collar of a 20 cm-high prostrate hemicryptophyte, vineyard, hill zone, Switzerland. Portulaca oleracea, tangential section.

Left Fig. 8. A small phloem with a unicellular external border of lignified sclerenchyma cells is in contact with the xylem. The lateral discontinuous phloem is embedded in the primary bark, which consists of large water storing parenchyma cells. Characteristic is the presence of some crystal druses. Root collar of a 20 cm-high prostrate hemicryp-sc tophyte, vineyard, hill zone, Switzerland. Portulaca oleracea, transverse section.

Right Fig. 9. Phloem with radial groups of sclereids and compressed sieve tubes (dark) between parenchyma cells. Root collar of a 20 cm-high dwarf shrub, on rock, hyperarid, Athacama desert, Chile. Cistanthe sal-soloides, tangential section.

Was this article helpful?

0 0
Get Fit Get Healthy

Get Fit Get Healthy

Anyone who wants to experience better health and fitness... Discover Simple Techniques To Getting Fitter Healthier And Staying That Way, Starting Today! This Guide Will Show You Easy Ways To Get Fit And Get Healthy No Fluff, No Fillers...Just Useful Techniques You Can Start Using Today.

Get My Free Ebook


Post a comment