18 ACADEMIC BOTANY. 



VI. -Estivation, or the arrangement of floral enve- 

 lopes in the bud. 



VII. Symmetry in the position, number, and form of 

 the floral -whorls. 



32. The Embryo rules the strudure of the leaf and stem. 



I. Oryptogamia : A. Class I. Naked Spores (Thallogens) 

 produce cellular growth without true leaves or stems 

 (Seaweeds, Liverworts) ; and 



B. Class II. Covered Spores (Acrogens) produce fork- 

 veined leaves (Ferns), or awl-shaped leaves (Club-Mosses), 

 and simple cellular stems with but little wood. 



II. Fhonerogamia. A. Class I. Uaked Seeds {Gymno- 

 spermm) produce parallel-veined leaves (Cycas), or fork- 

 veined leaves (Gingko), or awl-shaped leaves (Pines), with 

 imperfectly exogenous stems ; 



B. Class II. Covered Seeds {Angiospermoe), which have 

 two divisions : 



a. Monocotyledons, producing parallel-veined leaves 

 (rarely net-veined. Yam) and endogenous stems (Wheat, 

 Indian Corn, Banana, Palm). 



b. Dicotyledons, producing net-veined leaves and fiiUy 

 exogenous stems (Oak, Almond, Rose, Magnolia). 



33. Order of Classification. — Each Series — Cryptogamia 

 and Phanerogamia — has its Classes, Orders, Genera, and 

 Species. 



For example, the Dog-Eose (Rosa canina) and the Sweet-Brier 

 (Jiosa rubiginosa) differ in a few specific points, such as rustiness and 

 fragrance in the leaves of the Sweet-Brier ; they are therefore different 

 in Species (canina, rubiginosa). They are alike, how^ever, in fruit, 

 flower, leaf, and stem ; they are accordingly placed in the same Genus 

 (Rosa). The Peach and Almond resemble the Apple in flower ; but 

 the Apple-blossom has five pistils, whilst the Peach- and Almond- 

 blossoms have but one. Their fruit also differs from that of the 

 Apple ; they are therefore placed in a different genus (Prunus) from 

 that of the Apple (Pyrus). Yet the Peach, Almond, and Apple, in 

 their flowers, their seeds without perisperm and with a straight em- 

 bryo, resemble the Rose ; they are therefore placed in the Order of 

 the Eose (Rosacem). The Oak differs from all of these in flower, fruit, 

 and leaf; it Is therefore placed in a different Order (Oupuliferce). But 

 its seed is covered, — that is, it has a pericarp ; the Oak is accordingly 

 placed in the same Class with the Eose (Angiospermce, Covered l^eeds) ; 

 its embryo has two cotyledons, like the embryo in the Eose Order ; It 

 is therefore in the same Sub-Olass (Dicotyledonce). All these plants 

 have visible flowers producing seeds ; we know, therefore, that they 



