FLORA 



OF THE 



SOUTHEASTERN UNITED STATES 



SuBKiNGDOM PTERIDOPHYTA.^ Ferns and Fern Allies. 

 Plants containing woody and vascular tissues. They produce spores 

 asexually, each of which, on germination, develops into a prothallium 

 (gametophyte) . The prothallia bear the reproductive organs ; the female 

 organ is known as an archegone, the male as an antherid. As a result of 

 the fertilization of an egg in the archegone by a sperm produced in the 

 antherid, the asexual state of the plant is developed (sporophyte) ; this 

 phase is represented by a fern or an allied plant. 



Order 1. OPHIOGLOSSALES. 



Succulent plants consisting of a short fleshy rootstock bearing one or sev- 

 eral leaves and numerous fibrous, often fleshy, roots. Leaves erect or pendent, 

 consisting of a simple, lobed or compound sessile or stalked sterile blade and one 

 or several separate stalked fertile spikes or panicles (sporophyls), borne upon 

 a common stalk. Sporanges formed from the interior tissues, naked, each open- 

 ing by a transverse slit. Spores yellow, of one sort. Prothallia subterranean, 

 usually devoid of chlorophyll and nourished by an endophytic mycorrhiza. 



Family 1. OPHIOGLOSSACEAE Presl. Adder's-tongue Family. 

 Characters of the order. 



Veins reticulated: sporanges cohering in one or more distichous spikes. 



Terrestrial: spike single, long-stalked. 1. Ophioglossum. 



Epiphytic: spikes several, short-stalked. 2. Cheiroglossa. 



Veins free: sporanges distinct, borne in spikes or panicles. 3. Botrychium. 



1. OPHIOGLOSSUM L. 



Low terrestrial plants, with small erect fleshy rootstocks, and fibrous, naked roots. 

 Leaves 1-6, slender, erect, consisting usually of a short cylindric common stalk bear- 

 ing a simple entire lanceolate to reniform sessile or short-stalked sterile blade and a 

 single erect long-stalked spike, the sporophyl. Sporophyl formed of 2 rows of 

 large coalescent sporanges: spores copious, sulphur-yellow. Bud for the following 

 season borne at the apex of the rootstock, exposed, free. 



Leaf-blades ovate or elliptic-oblong, with several equal or parallel veins at the base. 



Leaf-blades obtuse or acutish: areolae with few veinlets. 1. O. vulgatum. 



Leaf-blades apiculate: areolae broader with many veinlets. 2. O. Engelmannii. 



Leaf-blades cuneate or cordate at the base, with unequal veins at the base. 



Rootstocks slightly tuberous: leaf-blades with a cuneate base. 3. 0. tenerum. 



Rootstocks globose: leaf-blades with a cordate base. 4. O. crotalophoroides. 



* Eevised for this edition by Mr. William E. Maxon. 



