a’ 7, 
OF THE GENUS PINUSe 599 
elliptical meristele. The hypoderm is in two rows. The resin- 
canals are in the centre of the mesophyll. The stalked deflexed 
cones are in whorls. In the young cone the apophysis is convex 
on both sides of the terminal subulate mucro, but in the older 
cones the umbo becomes shrivelled and depressed. 
39. Pinus rrerpa, Willer, Dict. (1768); Sargent, Silva, xi. 
(1897) p. 115; Beissner, Handbuch, p. 268, fig. 64 (1891). 
A native of the Atlantic States of North America, in sandy 
plains and dry gravelly uplands as well as on the coast. 
The leaves are in threes, each 8-14. cent., three-sided, the dorsum 
convex, the lateral faces concave and meeting in a prominent 
keel. Stomata are distributed all over the leaf. The leaf-section is 
three-sided, and shows a layer of thin-walled water-cells beneath 
the epidermis, between it and the hypoderm. The cell-walls in the 
mesophyll are infolded, and the resin-canals median. The endo- 
derm consists of about 40-50 cells. The meristele is oblong, 
and the fibro-vascular bundle branched, with bands of stereome- 
cells connecting the two phloem masses. 
The male flowers are slender, capitate, about 25 mill. long, 
each surrounded at the base by 6-8 scales. The cones are sessile, 
solitary or clustered, ovoid-oblong, with the free part of the 
apophysis somewhat triangular, slightly convex, dull brown. 
The cotyledons are 5. 
The species is very variable in the size and form of the cones, 
which, in some cases, so much resemble those of /. serotina, that 
some botanists have considered them to constitute a single 
species. 
P. rigida has the power of producing adventitious shoots from 
the old trunks, a peculiarity which it shares with P. serotina. 
40. P. serorina, Michaux ; Sargent, Silva, xi, (1897) p. 119. 
A species distributed from South Carolina to Florida (Sargent). 
In the living plants at Kew the herbaceous shoots are angular, 
deeply furrowed, glaucous, and clothed with leaves to the base. 
In the cortex is a single row of resin-canals. In the native 
specimens the male flowers are capitate, with 6-8 scales at the 
base of each. ‘The cones are sessile, spreading, broadly ovoid ; 
the apophysis slightly tumid, with a small deltoid mucro. 
The triangular leaves have median resin-canals, an oblong 
meristele, and a branched fibro-vascular bundle. The hy poderm 
is very thick, and the resin-canals are also provided with a 
