Characteristics of the phloem and the cortex

All species have sieve-tube groups (Figs. 36-38). They are arranged in more-or-less distinct tangential rows in all specimens with distinct xylem rings. Sclerenchymatic cell groups occur only in Thalictrum aquilegifolium (Fig. 39). Phellem was observed only in Aquilegia vulgaris (Fig. 40), Thalictrum alpinum (Fig. 41) and T. aquilegifolium.

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Left Fig. 26. Radial strips of vessels/parenchyma between large, indistinct rays. Semi-ring-porous arranged vessels indicate ring boundaries. Only vessel walls are ligni-fied. Rhizome of a 40 cm-high hemicrypto-phyte, Pinus mugo forest, mountain zone, Switzerland. Aquilegia vulgaris, transverse section.

Right Fig. 27. Radial strip (lobe) of vessels/ parenchyma between large rays. Slightly semi-ring-porous arranged radial multiple vessels indicate ring boundaries. Rhizome of a 10 cm-high hemicryptophyte, alpine meadow, Colorado, USA. Pulsatilla patens, transverse section.

Left Fig. 28. Radial strip of vessels/fiber (vascular bundle) between large rays. Semi-ring-porous arranged vessels indicate ring boundaries. Rhizome of a 10 cm-high hemicryptophyte, spruce forest, mountain zone, Piemont, Italy. Actaea spicata, transverse section.

Right Fig. 29. Radial strip of vessels/parenchyma between large rays. Semi-ring-porous arranged radial multiple vessels indicate ring boundaries. Rhizome of a 10 cm-high hemicryptophyte, volcanic rock, alpine zone, Colorado, USA. Thalictrum alpinum, transverse section.

Left Fig. 30. Thick-walled vessels are surrounded by unlignified pervasive parenchyma. Fibers are absent. Rhizome of a 10 cm-high hemicryptophyte, dry meadow, hill zone, Burgenland, Austria. Pulsatilla vulgaris, transverse section.

Right Fig. 31. Round intervessel pits. Rhizome of a 10 cm-high hemicryptophyte, dry meadow, hill zone, Burgenland, Austria. Pulsatilla vulgaris, radial section.

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Left Fig. 32. Slit-like intervessel pits. Rhizome of a 10 cm-high hemicryptophyte, alpine meadow, alpine zone, Ht. Savoy, France. Pulsatilla alpina ssp. millefoliata, radial section.

Right Fig. 33. Slit-like to scalariform inter-vessel pits. Rhizome of a 10 cm-high hemi-cryptophyte, volcanic rock, alpine zone, Colorado, USA. Thalictrum alpinum, radial section.

Left Fig. 34. Solitary and radial, multiple, lignified vessels are surrounded by unlig-nified pervasive parenchyma. Fibers are absent. Rhizome of a 10 cm-high hemi-cryptophyte, volcanic rock, alpine zone, Colorado, USA. Thalictrum alpinum, transverse section.

Right Fig. 35. Crystal druses in ray cells. Rhizome of a 10 cm-high hemicrypto-phyte, meadow, subalpine zone, Grisons, Switzerland. Thalictrum minus, tangential section, polarized light.

Left Fig. 36. Small groups of sieve tubes in the ray zone of the phloem. Rhizome of a 40 cm-high hemicryptophyte, Pinus mugo forest, mountain zone, Switzerland. Aquilegia vulgaris, transverse section.

Right Fig. 37. Groups of more-or-less tangentially arranged sieve tubes in the phloem. Rhizome of a 10 cm-high hemicryptophyte, spruce forest, mountain zone, Piemont, Italy. Actaea spicata, transverse section.

Left Fig. 38. Tangentially arranged groups of sieve tubes in the phloem. Rhizome of a 10 cm-high hemicryptophyte, Switzerland.

Thalictrum alpinum, transverse section.

Right Fig. 39. Groups of sclerenchymatic cells at the external side of the phloem between the rays. The cortex is covered by a phellem. Rhizome of a 10 cm-high hemi-cryptophyte, on volcanic rock, alpine zone, Colorado, USA. Thalictrum alpinum, transverse section.

Left Fig. 40. The cortex is covered by a phellem. Rhizome of a 40 cm-high hemi-cryptophyte, Pinus mugo forest, mountain zone, Switzerland. Aquilegia vulgaris, transverse section.

Right Fig. 41. A phellem covers a zone of callus cells above the xylem. Rhizome of a 10 cm-high hemicryptophyte, on volcanic rock, alpine zone, Colorado, USA. Thalic-trum alpinum, transverse section.

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