Anatomie. 83 



Cet appareil est encore plus d6veloppt§ dans la fleur oü toutes 

 les pi^ces deviennent des masses spongieuses ä mucilage. La graine 

 et le fruit en sont aussi abondamment pourvus. 



Le pistil a une valeur tricarpellaire. L'ovule forme plusieurs 

 sacs embryonnaires; la regiou interne de l'unique t^guinent fournit 

 une remarquable zone libero-ligneuse ä bois externe. 



Les Cassytiiacees sont des Lanracees modifiees par leur 

 parasitisme et dont l'appareil mucilagineux est particuliferement 

 caracterisd. C. Queva (Dijon). 



Plowman, A. B., The Comparative Anatomy and Phylogeny 

 of the Cyperaceae. (Annais of Botany. No. LXXVH. Vol. XX. 

 Jan. 1906. p. 1 — 33. With plates 1 — II and two figures.) 



The internal structure of the root of the Cyperaceae is of the 

 usual Monocotyledonoiis type and is very uniform. The rhizogenous 

 pericambium is generally interrupted at the xylem plates, and the 

 rootlets arise opposite a phloem Strand, their xylem elements being 

 derived from the two adjacent xylem Strands. In some cases the 

 pericambium is incomplete and the rootlets then arise opposite the 

 xylem Strand with which they are connected. The rhizome is of 

 very general occurrence, in rnost cases giving rise to a few aerial 

 shoots, each of which ultimately developes flowers. The central 

 cylinder of the rhizome is usually solid and is surrounded by an 

 endodermal sheath; the cortex is very variable and may be sclerotic, 

 aerenchymateous, or consist of unmodified parenchyma. In the 

 seedling the central cylinder is a siphonostele of the phyllosiphonic 

 type, Ihe collateral medullary bundles arising rather early, 



Two groups can be distinguished depending on the structure 

 of the central cylinder of the rhizome of the mature plant. The 

 Amphivasae bear conspicuous leaves at all the nodes and the inter- 

 nodes are relatively short; all or most of the bundles are amphi- 

 vasal or concentric, the xylem surrounding the phloem, and each 

 usually possesses a large centripetal mass of sclerenchyma. A dense 

 plexus of transverse and oblique fibrovascular Strands occurs just 

 inside the endodermis, to which all the root Strands and many of 

 the smaller leaf-trace bundles are attached. The larger leaf-trace 

 and ramular bundles pass inwards to the medulla and then outwards 

 to the superficial plexus. In the Centrivasae the bundles are much 

 less numerous and are of the collateral type with xylem on the 

 centripetal sine; the rhizomes bear only small or scattered leaves. 

 There is no superficial plexus, the root Strands being attached to 

 the superficial bundles of the cylinder. A generic key based on the 

 characters of the central cylinder and a table presenting the chief 

 features of the rhizome in the more interesting species are given. 



The aerial stem is generally a jointed culm with few or many 

 long internodes but it may assume a scapose habit. It is commonly 

 derived by bifurcation of the growing point of the rhizome and at 

 its origin it leaves a large endodermal gap through which cortex 

 and medulla communicate. The cauline bundles are continuous with 

 the medullary bundles of the rhizome, and in the base of the culm 

 they increase considerably in number by branching; they are always 

 collateral. The bundles of the first sheath are derived from the 

 superficial plexus of the rhizome. Two classes can be formed based 

 on the relative prominence of mechanical and assimilatory tissue in 

 the cortex. The Chlorocyperaceae contain a cortical assimilatory 

 zone made up of several layers of palisade cells. The cuticle is 



6* 



