94 



MEMOIRS OF THE NEW YORK BOTANICAL GARDEN 



LVOL. 10 



Orectanthe. 



1. 0. ptaritepuiana. The sepal of this species consists wholly of lignified 

 parenchyma, except in the central portion of the keel, where thin-walled 

 parenchyma occurs. This thin-walled parenchyma presumably contains a 

 moderate number of chloroplasts, as it does in 0. sccptrum. 



2. O. sceptrum. As shown in figure 64, sepals of 0. sceptrum subsp. oc- 

 cidentalis are like those of 0. ptaritepuiana except that pockets of thin-walled 

 parenchyma, like that in the keel region, occur in the wing regions between 

 veins. Liquid-preserved material was used to demonstrate the presence of 

 chloroplasts in this soft-walled parenchyma. The central portion of a flattened 

 sepal of this species, shown in figure 21, illustrates these same structural 

 features. 



Achlyphila. 



The three sepals of Achlyphila disticha (fig. 65) are rounded rather than 

 keeled. They contain about five bundles, which are embedded in the thin-walled 

 parenchyma, composed of cells polygonal in outline, in the central portion of 

 the sepal. This parenchyma contains chloroplasts in moderate numbers. The 

 inner and outer faces of the sepal are sclerenchyma. At lower levels, this 

 sclerenchyma takes the form of lignified parenchyma which intergrades with 

 the thin-walled parenchyma in the center of the bract, but at higher levels, 

 such as that shown, the sclerenchyma is thick-walled and clearly definable from 

 the chlorenchyma. 



Discussion. 



The sepals of Orectanthe are different from those of Abolboda in that (1) 

 they are much larger; (2) they consist wholly of lignified parenchyma cells 

 except for pockets of chlorenchyma in the keel and between some of the veins; 

 and (3) they contain a much greater number of veins, and veins have a 

 scattered distribution in the keel region. Sclerenchyma is present around veins 

 in Orectanthe sepals regardless of location of veins. Sepals of Achlyphila are 

 very simple in structure, corresponding with other seemingly unspecialized 

 features of this genus. The presence of both an adaxial and an abaxial band 

 of sclerenchyma, together with the lack of a keel, is notable. The species of 

 Abolbodd seem to agree in their tendency toward production of an adaxial 

 sclerenchyma band, and in the relative paucity of sclerenchyma in the abaxial 

 portion of the sepal. Only a single series of bundles is present (unlike the 

 condition in Orectanthe) . The patterns of distribution of sclerenchyma, thin- 

 walled parenchyma, and chlorenchyma undoubtedly lend themselves to use as 

 specific criteria, and are self-evident, in the varied patterns illustrated, in 



Fig. 56-65, sepals, transections t^aken about midway along length of sepal; half of a keeled 

 sepal is shown for each species. Fig. 56. Abolboda acaulis. Fig. 57. A. acicularis var. 

 acicularis. Fig. 58. A. americana. Fig. 59. A. ciliata. Fig. 60. A. line an folia.. Fig. 

 61. A. macrostachya var. angustior. Fig. 62. A. macrostochya var. robustior. Fig. 63. A. 

 sprucei. Fig. 64. Orectanthe sceptrum. Fig. 65. Achlyphila disticha. Fig. 66. Achlyphila 

 disticha, transection of bract of inflorescence proper. Patterns as follows: fine stippling = 

 thick-walled sclerenchyma ; coarser stippling = thin-walled sclerenchyma ; cross-hatched = 

 chlorenchyma; white in bundles = phloem; black = xylem ; parenchymatous ground tissue 

 left blank. Scale == 2 mm in 1 mm divisions; applies to all figures. 



