Spelling variants where it wasn't possible to determine the author's intent were left as is. These include: "backbone" and "back-bone;" "Buttonwood" and "Button-wood;" "cross section" and "cross-section;" "footstalk" and "foot-stalk;" "network" and "net-work;" "Pæony" and "Peony;" "peapod" and "pea-pod," plus plurals; "penniveined" and "penni-veined," plus capitalized versions; "Sapwood" and "Sap-wood;" "Snowball" and "Snow-ball;" "Verticil" and "Verticel;" "Woodsorrel" and "Wood-sorrel." Changed "Venation" to "Vernation" on page vi: "Vernation or Præfoliation." Changed "Isoëtes" to "Isoetes" on page viii: "Quillworts (Isoetes)." Changed "liquifies" to "liquefies" on page 21: "as it liquefies." Changed "frame-work" to "framework" on page 52: "the framework or skeleton." Changed "leafstalk" to "leaf-stalk" in three places: the caption to figure 74; on page 71: "bent upon the leaf-stalk;" in the index entry for "Petiolulate." Changed "Honey Locust" to "Honey-Locust" in the caption to figure 95: "branching thorn of Honey-Locust." Page 47 has a reference to Fig. 89, which does not seem to follow from the text. "Fig. 80" would make more sense, but the original was not changed. Removed extra comma before closing parenthesis on page 51: "the Maple (Fig. 20, 24)." Changed "Linnaeus" to "Linnæus" on page 50: "Linnæus called Nerves." Changed "Sugar-Maple" to "Sugar Maple" on page 58: "that of the Sugar Maple." Changed "quadrifoliate" to "quadrifoliolate" on page 59: "trifoliolate, quadrifoliolate, plurifoliolate." The reference to Fig. 167 on page 64 is probably intended to refer to Fig. 157, but was not changed. The caption to figure 186 says that this is a two-ranked arrangement. Although it's clear from the text and figure that this is actually a three-ranked arrangement, the original text was preserved. Changed colon to semi-colon in the caption to figure 219: "a, filament; b, anther." Changed comma to period after "Fig. 254" in its caption. Changed "Funnel-form" to "Funnelform" on page 90: "Funnel-shaped, or Funnelform." Inserted closing parenthesis in caption to figure 304: "Of a Sage (Salvia Texana)." Changed "Butter cup" to "Buttercup" on page 120: "fruit of the Buttercup." Changed "carpophorse" to "carpophore" on page 121: "a slender axis or carpophore." Changed "cocoanut" to "cocoa-nut" on page 122: "such as the cocoa-nut." Changed "Sepifragal" to "Septifragal" on page 123: "Septifragal dehiscence." Inserted missing text "(Fig." on page 128: "Rice (Fig. 430a)." Perhaps the reference to unit 408 on page 136 should be to unit 402; but it was not changed. Changed "White-Pine" to "White Pine" on page 148: "White Pine and Basswood." Changed "discovary" to "discovery" on page 160: "discovery of a wholly unsuspected kind." Changed "sporo-carps" to "sporocarps" in the caption to figure 520. Changed semi-colon to period after "microspores" in the caption to figure 522.