ECOLOGIC SUBTERRANEAN ANATOMY OF PLANTS 
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Gross structure: Slender, hard rhizome with clusters of filamentous roots. 
Histology of rhizome (Plate XXIV, fig. 2) : 
Primary cortex: Depth 1/4 radius of root; cork 4 rows; parenchyma compact. 
Stele; Bundles radial, distinct; phloem protected by patches of bast; vessels few; 
wood parenchyma cells large; bast sheath prominent; pith parenchyma compact. 
Summary: Parenchyma well developed but compact; mechanical tissue conspicuous 
around bundle; xylem tissue sparse. 
Antennaria plantaginifolia (L.) Richards. 
Habitat: Dry hill crests and slopes. 
Gross structure: Slender, radially extensive rhizomes with fringes of slender roots at 
their nodes. 
Histology of rhizome (Plate XXVI, fig. i): 
Primary cortex: Depth 1/4 of radius of root; cork 1/4 of cortex; parenchyma thin- 
walled, rectangular; endodermis thin-walled. 
Stele : Collateral bundles ; phloem unprotected, rectangular cells ; thick parenchyma 
rays separate the bundles ; xylem with annular rings marked by layers of wood 
parenchyma at beginning of ring and thick-walled wood fibers at end; pith 
parenchyma large-celled, rather spongy. 
Summary: Cork well developed; mechanical tissue in form of wood fibers prominent. 
Liatris squarrosa Willd. 
Habitat : Slopes, rather dry. 
Gross structure: Stem corm-like, hard, flinty; somewhat scaly on surface; bears clus- 
ters of small filamentous roots. 
Histology of corm (Plate XXVIII, fig. 2): 
Primary cortex: Depth 1/6 radius of corm; cork 1/7 of cortex; cortical parenchyma of 
brick-like cells among which are a few sclerids; resin ducts present, bordered 
by 2 rows of thin parenchyma cells; endodermis not distinct. 
Stele: Collateral bundles; clusters of sclerenchyma cells arranged around the per- 
imeter of the phloem strands; parenchyma thin-walled; xylem in a series of 
clusters of annular growth; clusters of wood parenchyma and tracheae formed 
in spring; wood fibers formed in fall; xylem surrounded by fairly thick-walled, 
elongated parenchyma cells; resin ducts numerous throughout parenchyma; 
central pith of roundish cells. 
Summary: Mechanical tissue prominent; resin ducts conspicuous; parenchyma com- 
pact. 
SoUdago canadensis L. 
Habitat: Moist slopes; sometimes dry places. 
Gross structure : Abbreviated rhizome with slender clusters of short roots. 
Histology of rhizome: 
Primary cortex: Depth 1/6 radius of rhizome; hypodermis of mechanical cells; 
parenchyma rather thick-walled; endodermis not distinct. 
Stele: Collateral bundles; points of bast above tips of phloem; xylem fascicles 
branched outside of the second annular ring; broad bands of wood parenchyma 
cells separate the bundles; zones of parenchyma cells are left in spring growth; 
wood fibers appear in bands in fall growth. 
Summary: Mechanical tissue prominent; tracheae fairly large. 
Histology of root : 
Primary cortex: Depth 1/2 radius of root; thick band collenchyma; parenchyma 
fairly thick-walled; endodermal walls not thickened. 
Stele: Radial bundles show exarch arrangement of primary xylem; mechanical 
tissue fills center of cylinder; tracheae large. 
Summary: Cortex deep; conspicuous mechanical tissue; large tracheae. 
Heliopsis scabra Dunal. 
