Amentales.] 



CASUARINACEyE. 



240 



Okder LXXVII. CASUARINACEjE.-Beefwoods. 



Casuarineae, Mirb. in Ann. Miis. 16. 451. 



1810) ; R. Brown in Flinders, 2, 571. Endlich. Gc/j.lxxxvi 

 Meisner, p. 35h 



Diagnosis. — Amental Exogens, loitk a \-cellecl ovary, 1 or 2 mcending ovules, and a 



supenor radicle. 

 Branching weeping trees, with jointed shoots, the interuodes of which are striated. 

 Leaves ; hi then- room short, toothed, ribbed sheaths. 

 Flowers m spikes, $ $ , each with a single bract. $ in 

 spikes. Flowers whorled about the articulations of the 

 jointed I'achis. Bracts 2, membranous, right and left 

 of a two-leaved calyx, the sepals of which stand fore 

 and aft, and adhere at their points, and at the time of 

 flowei'ing are separated from their bases and carried 

 up by the stamen in the form of a calyptra to the anther. 

 Stamen 1 ; filament subulate ; anther erect, two-celled, 

 with pai-allel contiguous cells opening by a longitudhial 

 fissure. $ : In dense heads. Rachis not jointed. 

 Calyx 0. Ovary one-celled, with one obliquely ascend- 

 ing orthotropal ovule, or two standing side by side. 

 Styles 2, united at base. Caryopsides winged, collected 

 in a cone, hidden in thickened bracts, sessile. Seed 

 erect, coated densely with spiral vessels, without albu- 

 men ; i-adicle superior. 



These are jointed, leafless, tropical, or sub-tropical 

 trees, with all the appearance of an Equisetmn. Blume 

 remarks, that " Casuaruia is undoubtedly related to 

 Myrica in its ovaries, its single erect o\Tile, and its 

 exalbuminous inverted embryo ; but it differs so much 

 in its habit, that it is better, with IMirbel, to consider it 

 a distinct family, which differs from Galeworts in its 

 fructification, especially in its achenia with membran- 

 ous wings included between two lateral scales, which, 

 as they gi'ow up, are collected into a compact cone. 

 Myrica, on the contrary, has distinct dinipes, each 

 somewhat immersed in a somewhat fleshy involucre 

 (or calyx), which, although at first hypogynous, is 

 eventually, after fecundation, extended beyond the 

 ovary, with which it is conglutinated. Of such an in- 

 volucre there is no trace in Casuarina, since the lateral 

 scales, surroundmg each achenium like a 2-valved cap- 

 sule, by no means answer to the calycine involucre of 

 Galeworts, but rather to those inferior 

 bractlets which we observe at the base of 

 the drupes in that Order." 



The peculiar jointed leafless stems of 

 these plants necessarily suggest a relation- 

 ship to Ephedra among Gymnosperms ; 

 and it is indeed probable, that Casuarina 

 offers more distinctly than any other Exo- 

 gen the passage from Angiospermous to 

 Gymnospermous Orders. Endhcher de- 

 scribes the ovule as pendulous ; Bhnnc, 

 as erect. Neither are right. At least, the 

 half-grown ovule is obliquely ascending 

 from a little way up the side of the ovarian cavity, with a large foramen at the apex. 



Fig. CLXVII.— 1. Casuarina ; 2. ^-,3. ^ flower; 4. ^ flower; 5. the ripe valves of the calyx, 

 from which the fruit has been t.iken ; fi. a section of the half ripe ovary ; 7. a section of the fruit show- 

 ing the seed and embryn. 



