100 



gular patches, — a circumstance which arises from the rigidity of its tissue, 

 on account of which it is incapable of stretching as the wood Ijeneath it 

 increases in diameter. 



Example. Platanus. 



LXXXVI. MYRICE^. The Gale Tribe. 



MyeicE/F., Itich. Anal, du Fr. (1808); Ach. Rich. EUm. de la Bot. ed 4. 561. (1828); 

 Lindl. Synops. 242. (1829) — Casuarine^e, Mirbel in Ann. Mm. 10. 451. (1810) ; 

 R. Brown in Flinders, 2. 571. (1814.) 



Diagnosis. Achlamydeous dicotyledons, with a 1-celled ovarium, erect 

 ovules, a naked embryo, and amentaceous flowers. 

 Anomalies. Casuarina is leafless. 



Essential Character — Floicers unisexual, amentaceous. AInles : S/amens 1 

 or several, each with a hypogynous scale. Anthers 2- or 4-celied, opening lengthwise. 

 Females: Ovarium 1-celled, surrounded by several hypogynous scales; ovulum solitary, 

 erect, with a foramen in its apex ; stigmas 2, subulate. Fruit drupaceous, often covered 

 with waxy secretions, formed of the hypogynous scales of the ovarium, become fleshy and 

 adherent; or dry and dehiscent, with the scales distinct. Seed solitary, erect; embryo 



without allmmen ; cotyledons 2, plano-convex; radicle short, superior Leafy shrubs, 



with resinous glands and dots, the leaves alternate, simple, with or without stipulse ; or 

 leafless shrubs or trees, with filiform branches bearing membranous toothed sheaths at the 

 articulations. 



Affinities. The nearest approach made by these plants is probably to 

 Ulmaceae and Betulineee, from the former of which they are readily known 

 by their amentaceous flowers and want of a perianthium ; from the latter they 

 are distinguished by their erect ovula, aromatic leaves, and 1-celled ovarium. 

 In the latter respect they resemble Piperacese, from which, however, they 

 differ materially in other points. The only anomalous genus is Casuarina, 

 which has the habit of a gigantic Equisetum, and which can scarcely be 

 compared with any other dicotyledonous tree. Mr. Brown, in the Appendi.K 

 to Flinders' s Voyage, has the following observations on the stnicturfe of this 

 remarkable genus, from which it will be seen that he does not consider it 

 achlamydeous, as I do. 



*' In the male flowers of all the species of Casuarina, I find an envelope 

 of four valves, as Labillardiere has already observed in one species, which he 

 has therefore named C. quadrivalvis. Plant. Nov. Hall. 2. p. 67. t. 218. 

 But as the two lateral valves of this envelope cover the others in the unex- 

 panded state, and appear to belong to a distinct series, I am inclined to 

 consider them as bractese. On this supposition, which, however, I do not 

 advance with much confidence, the perianthium would consist merely of the 

 anterior and posterior valves ; and these, firmly cohering at their apices, are 

 carried up by the anthera, as soon as the filament begins to be. produced, 

 while the lateral valves or l)ractetp are persistent; it follows from it, also, that 

 there is no visible perianthium in the female flower; and the remarkable 

 economy of its lateral bractets may, perhaps, be • considered as not only 

 affording an additional argument in support of the view now taken of the 

 nature of the parts, but also as in some degree again a[)proximating Casu- 

 arina to Coniferse, with which it was Ibrmcrly associated. The outer coat of 

 the seed or caryopsis of Casuarina consists of a very fine membrane, of which 

 the terminal wing is entirely composed ; between this membrane and the 

 crustaceous integument of the seed, there exists a stratum of spiral vessels, 

 which Labillardiere, not having distinctly seen, has described as an ' integu- 



