CLASS XXII. ORDER I. 119 



A. IViih annulated ca/isules, 

 1. Without involucres. 



Acrostic HUM. Capsules numerous, covering 

 the ^vhoIe lower surface of the frond. (The fertile 

 leaves differ in shape from the barren. This genus 

 should be examined in the young state ; for the scat- 

 tered fruit of other genera, by becoming coniluent 

 when old, often cover the frond.) 5 5. 5 — aureum 

 (fork-fern) frond pinnate with alternate leafets, fruit 

 on the upper leafets 2/. 



PoLYPODiuM. Capsules disposed in round scat- 

 tered dots, on various parts of the lower surface of 

 the frond. 55. 5 — vulgare^ (polypod) frond pinnati- 

 fid with oblong obtuse sub-serrate lobes, root with 

 chaffy scales — incanum, same, with lobes lanced 

 entire — virgiiuanum^ root smooth — connectile, frond 

 doubly-pinnate, ciliate, fruit-dots minute — calcare- 

 "untj frond ternate and doubly-pinnate. 



2. With involucres, 



Onoclea. Fruit-dots indeterminate, capsules 

 covering the whole lower surface of the frond : in- 

 volucre formed by turning in or rolling back the 

 margin of the leaf, which opens inwards, in maturi- 

 ty, towards the midrib. (The fertile leaves are 

 contracted and narrower than the barren ones.) 55. 

 5 — sensibilis, (sensitive polypod) barren frond pin- 

 nate, fertile one doubly-pinnate struthiopteris^ 



fronds doubly-pinnatifid, divisions roundish. 



Blechxum. Capsules in uninterrupted lines 

 running parallel to the midrib of the frond on both 

 sides : involucre opens inwards. f (The fruit of 



■f The involucre opens vuvards, when it opens or sepa. 

 rates, so as to leave tlie capsules naked on the side next ta 

 the midrib. 



L 2 



