48 DESCBIPTIOKS OF TWO NEW DILLENTACEOUS PLANTS. 



to three, and from all but a few Pleurandrte and Hibbertice, in the 

 solitary ovary. In respect of the irregular corolla it approaches Hemi- 

 stemma, in which two of the petals are occasionally smaller than the 

 others, and unsymmetrically arranged ; in that genus however the irre- 

 gularity is shared by the stamens to even a greater degree, whereas in 

 Trisema the staminal whorl is perfectly regular. It is further worthy 

 of notice, that the ovary being solitary in Trisema is another irregula- 

 rity, the normal disposition of the female organs in the Order being a 

 whorl ; there are here, therefore, regular calycine and staminal whorls, 

 and irregular corolline and ovarian ones ; whereas in Hemistemma all 

 the whorls but the calycine are irregular, the staminal being most so ; 

 in Pleurandra the ovarian and staminal whorls alone are irregular ; 

 and in Hibbertia and others the ovarian only. This irregularity of the 

 flowers is as prevalent a feature in the closely allied Order Ranuncu- 

 lacea>> from which indeed Dilleniacea are chiefly distinguished by the 

 shrubby or arboreous habit of most, their coriaceous, invariably per- 

 sistent sepals, the almost constant presence of an arillus, and they fur- 

 ther want that tendency to a multiplication of the corolline and ovarian 

 whorls so conspicuous in JRanunculacece. 



The irregularity of the flowers of Dilleniacece should be taken into 

 account in all attempts to explain the origin and relations of the floral 

 organs and whorls in Ranunculacea ; and considering these Orders as 

 forming parts of one group, few are more instructive in this respect, 

 from the number of instances both of total suppression and of great 

 multiplication, which they present. 



Plate I. Fig. 1. bud. 2. Flower, laid open. 3. Stamen. 4. 

 Ovary. 5. Vertical section of ovary. 6. Ovule : — all magnified. 

 2. Hemistemma candicans, Hi. ; ramulis cinereo-pubescentibus apice 

 angulatis, foliis breve petiolatis anguste lineari-lanceolatis acutis 

 supra glabratis subtus tomento niveo arete appresso tectis nervis 

 et costa glabratis, racemis axillaribus abbreviatis paucifloris, pedun- 

 culis foliis brevioribus 2-5-floris cinereo-pubescentibus, floribus sub- 

 sessilibus, petalis obcordatis 3 superioribus majoribus, staminibus 

 biseriatis serie exteriore linearibus anantheris basi connatis, ovariis 2. 



(Tab. II.) 



orientali tropica ad Cap. York. (/. Macgillivray 



legit, itiuere navarchi Stanley, October, 1S48.) 

 //. dealbata proxima, sed differt foliis angustioribus supra medium 



