700
ELEMENTS OF MATERIA MEDICA.
3. EXOG'ENiE, Decavd.— EX'OGENS.I Dicotyledones, Jussieu .
Fig. 135.
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i mi
(d) Transverse section of a dicotyledonousstem,shewing medullary rays, and thedistinction of bark, wood, and pith.(t») Embryo with two cotyledons.
(x) Embryo with four cotyledons.
( V) Embryo with many cotyledons.
(z) Stem and leaves of a dicotyled 1 ’ ’shewing the articulation andanastomosing veins of the leave 3-
Essential Characters. — Trunk, consisting of bark, wood, and pith, placed one ' #n( jthe other; the pith being innermost. Bark, composed of strata (the young®inner being called liber), increasing by the deposit of new cortical matter on it 3side. Wood , consisting of ligneous strata, traversed by medullary rays, and mere ^j efby ihe deposit of new woody matter on its outer side {exogenous growth). l ‘i eand inner strata are called duramen, or perfect wood ; the younger and outer ^. ))Sare termed alburnum, or sap wood. Leaves articulated with the stems; ^ jj s ii» clbranching and anastomosing (angulinerved j reticulated). Flowers, if with R , ,j 0 tpcalyx, often having a quinary arrangement. Embryo with two more c0 X • jj a te •(dicotyledonous ): if two, they are opposite; if more than two, they are vertiradicle naked; i.e. elongating, without penetrating any external case ( exorrhi~
Order 20. Cycada'ce^, Lindley. —The Cy'cas Tribe.
Fig. 136.
('yeas revoluta,or, the Japan Sago tree.
‘S.
§e
I notice this order for the .P ur ? ta iiie4,stating, that a feculent matter is 0 . s <jffrom the soft centre of some speCycas (as C. circinalis, C. revo u . ’ u iteC.inermis). This lecula (Japan sago)unknown to me; and I doubt whet iereaches this country. (Consult on -j \g-
ject Schenk’s Naturgeschichte a& ^ td'-b
lichsten Handelspflanzen,iio.D<l. >
Taf. xlvi.)