Vegetative Anatomy — Carlquist 
203 
margins of the leaf and branches are given 
off toward the margin, whereas in Ar^roxi- 
phium the branches are given off toward the 
midveins. Dubautia resembles Wilkesta in this 
respect. In Ar^roxiphium (Carlquist, I9^7d, 
fig. 17), however, the alternate leaves are re- 
lated to multilacunar nodes, and adjacent 
laterals of successive leaves in the spiral are 
united below the leaf base. 
Dubautia, Arg^roxiphium, and Wilkesia, then, 
are amply distinct from each other in nodal 
anatomy. The taxonomic interest of the dif- 
ferent types within Dubautia seems evident; 
the phylogenetic relationship of the various 
types in the three genera, however, will be 
better understood when greater knowledge of 
nodal anatomy in Compositae at large is 
available. 
Pith 
The wide range of pith types in Dubautia 
is suggested by comparison of Figures 15-18 
(see also Figs. 21, 22, right). As with patterns 
of leaf construction, these can be referred to 
a number of types; these should not be re- 
garded as categories, however, although some 
reflect natural assemblages of species: 
1. D. plantaginea (Fig. 15). Pith cells thin 
walled with small intercellular spaces; 
periphery (inner margins of bundles) scle- 
rified; secretory canals present (opposite 
inner faces of larger bundles); no car- 
bonized resin deposits present. 
Like D. plantaginea: 
D. microcephala, D. railliardioides, D. 
lonchophylla (virtually identical with 
D. plantaginea ) . 
D. paleata (peripheral sclerenchyma 
very thick walled). 
D. scabra (secretory canals infrequent) . 
D. magnifoUa (periphery unsclerified) . 
D. ternifolia (patches of sclereids pres- 
ent throughout pith). 
D. Knudsenii, D. platyphylla, D. laxa, 
D. ciliolata (secretory canals ab- 
sent) . 
D. thyrsiflora (no secretory canals; 
some cells in center of pith scleri- 
fied; carbonized resin deposits in 
intercellular spaces). 
D. laevigata (no secretory canals; en- 
tire pith sclerified, more markedly 
so at periphery). 
2. D. linearis (Fig. 16). Entire pith sclerified, 
not more so at periphery than at center; 
intercellular spaces small; no secretory 
canals; carbonized resin deposits not 
observed. 
Like D. linearis: 
D. Sherjjiana, D. reticulata (carbonized 
resins in intercellular spaces). 
3. D. latifolia (Fig. 17). Pith thin walled ex- 
cept at periphery, where it is prominently 
sclerified, and in the center, where nests 
of sclereids occur; the central sclereids are 
much narrower in diameter than other 
cells of the pith; intercellular spaces small; 
secretory canals absent; carbonized resin 
deposits in intercellular spaces of thin- 
walled area of pith. This pith type appears 
to be a marked specialization over the 
preceding types. 
4. D. Menziesii (Fig. 18; Fig. 21, right). Pith 
highly lacunose, owing to large intercel- 
lular spaces; periphery consisting of small 
fiberlike sclereids adjacent to bundles; 
remainder of pith composed of large cells, 
both sclerified and unsclerified; no secre- 
tory canals; carbonized resins abundant in 
intercellular spaces. Figure 21 shows an 
early stage in the development of this 
pith, whereas pith from an old stem is 
shown in Figure 18. The progressive scle- 
rification is evident, although some thin- 
walled cells remain in the pith shown in 
Figure 18. 
Like D. Menziesii: 
D. montana, D. struthioloides, D. Hille- 
brandii (virtually identical with D. 
Menziesii ) . 
D. arborea (fewer sclereids). 
This type of pith would seem to represent 
a specialization over the condition indi- 
cated for D. plantaginea. An intermediate 
