242 MORPHOLOGY OF ANGIOSPERMS 



recently received more deserved attention from morphologists, 

 and which still so greatly needs investigation. 



I. CASUARINALES.* This includes the single family Casu- 

 arinaceae, containing about 25 species. Engier regards the al- 

 liance as the most primitive because the ovule develops numer- 

 ous megaspores. This particular character can not be regarded 

 as distinctive, since among the Fagales the same character, 

 associated also with chalazogamy, occurs, and numerous mega- 

 spores are found among the Ranales, Resales, etc. The low 

 position, however, is justified by the primitive flowers, which 

 are either naked or with a bract-like perianth. 



The next two alliances are regarded as relatively primitive 

 on account of their naked flowers, together with the Casuari- 

 nales being the only naked alliances. 



II. PIPERALES. This includes the Saururaceae, Pipera- 

 ceae, Chloranthaceae, and Lacistemaceae, together containing 

 about 1,150 species, of which about 1,100 belong to the Pipera- 

 ceae. The results of the investigation of Peperomia pcllucida 

 by Campbell and by Johnson indicate that the tropical Pipera- 

 ceae are probably most promising forms for morphological 

 investigation, and are to be considered in any discussion as to 

 the most primitive Dicotyledons. 



III. SAI/TCALES. This includes the single family Salica- 

 ceae, containing about 180 species. 



IV. MYRICALES. This includes the single family Myrica- 

 ceae, containing 40 species. The advance in floral structure is 

 shown by the fact that the several bracts near the flower may 

 be regarded as an extremely primitive perianth. 



V. BALANOPSIDALES. This includes the single family Ba- 

 lanopsidaceae, containing 7 species. This is an uncertain type, 

 and raises the question of reduction. The staminate flowers 

 have a rudimentary perianth and an indefinite number of sta- 

 mens; and the carpellate flowers have a bracteate perianth. 

 Engier calls attention, however, to the fact that there are no 

 intermediate forms for a reduction series, and that the indefi- 

 nite number of stamens is a primitive character. 



VI. LEITNERIALES. This includes the single family Leit- 

 neriaceae, containing 2 species. The primitive character of this 



* VERTICILLATAE of Engier. 



