608 THE STEMS OF CLIMBING PLANTS, 



ii. MONOCOTYLEDONES. 



1. Vulgares, — To this section belong Asparagus racemosus 

 Willd., Flayellaria indica Linn., Geitonoplesium cymosum A. 

 Cunn., Rhipogonum album R.Br., and Sviilax australis R.Br , tfec. 



2. Abnormales. — Galeola cassythoides Reichb. f., (PL Ixvi., 

 fig. 14). — In this leafless, climbing orchid, the bundles are numer- 

 ous, and contain six large vessels, with a few smaller marking 

 the protoxylem. In each vascular bundle there is a limited 

 quantity of soft bast, and a few sieve-tubes. The ground-paren- 

 chyma is formed of larger cells than usual, and these are massed 

 round the bundles, forming bundle-sheaths. In transverse sec- 

 tions of the stem, a roughly radiate arrangement of the cells of 

 the ground-parenchyma is evident, in some sections showing four 

 rays, in others with more and irregular rays. Numerous sacs 

 containing raphides are seen in the ground-tissue. The contents 

 of cells lying immediately within the bark show a brown dis- 

 coloration; these are evidently attacked by a parasitic fungus, 

 whose hyphte can be seen within the brown cells. 



Conclusion. — The whole of the abnormal stem-structures in 

 climbing plants have, for their object, the free flow of elaborated 

 sap in the bast-tissues. In Chiastoxylon, the stem so presses on 

 the support as not to put pressure on the bast-masses ; in 

 Astroxylon, the broad medullary rays ensure the nutrition of 

 the stele; in Hiptage, Bryonia, and Solanum Wendlandii, a thick 

 pad of elastic cork is developed on that side of the stem subject 

 to pressure, and so on. 



Reference letter.^. — h., Bast — c, Cambium — c.c, Cork-cambium — ck., 

 Cork — cr., A crj^stal— ec. , Protoxylem— //>. , Fibro-vascular bundle — //., 

 Hair — m.r., Medullary ray— ^., Pith^pA., Phelloderm — r.d., Resin -duct 

 — ry., (Fig. 14), Three of the four rays traversing the ground-parenchj^ma 

 — .§., Sclerotic cells — sc, Sclerenchyma — 4.y.6. (Fig. 14), Secondary vascular 

 bundles — t.t., Transfusion-tissue — c, Vessels of wood — i:.h. (Fig. 14), Vas- 

 cular bundle with apparent bundle-sheath — w.. Wood — x (Fig. 14), Traces 

 of fungal hypha;. 



