The type of key used in this manual is prob- 

 ably familiar to most investigators. It consists 

 of two statements of contrasting characters. The 

 user makes a choice of the one which fits the 

 plant in hand. This will lead to a number which 

 will take him to another pair of characters where 

 he again makes a choice. This eventually leads 

 to a specific plant name. In order to permit 

 working in reverse, the number of the preceding 

 character is given in parenthesis. 



A complete collection of the plants included 

 in this key has been deposited in the Herbarium 

 of the Gray Museum, Marine Biological Labora- 

 tory. 



GLOSSARY 



The use of technical botanical terms has been 

 kept to a minimum. Those found to be neces- 

 sary are included in this glossary. Terms used 

 to describe leaf shapes, tips, and margins, and 

 the juncture of sheath and blade in grasses are 

 illustrated in Plate I. 



achene a small, dry, one-seeded fruit that does 



not open at maturity. 

 acuminate see Plate I. 

 acute see Plate I. 

 apical relating to the apex or tip. 

 auricle an ear shaped appendage or lobe (see 



grass, Plate I). 

 axile in the angle between two structures. 

 hract a modified leaf subtending a flower, some- 

 times on the stem. 

 capsule a dry fruit that opens when ripe and 



with more than one-seed cavity. 

 caudex the persistent base, sometimes woody, 



of an herbaceous stem. 

 clasping in which the base of the leaf partially 



encircles the stem (see Fig. 47). 

 corymb a flat topped or convex open flower 



cluster. 

 cryptogams lower plants, nonflowering. 

 deciduous not persistent, not evergreen. 

 dioecious male and female elements in separate 



plants (two households). 

 drupe a fleshy fruit with a stone seed. 

 filifo)-m threadlike. 

 glume a chaff'like bract at the base of the spik- 



let in grasses. 

 imbricated overlapping. 

 involute rolled inward. 



leaf shapes and m,argins see Plate I. 



lenticels corky spots on the young bark of trees 



and shrubs. 

 ligule a projection from the summit of the 



sheath in grasses (see Plate I) ; the flattened 



limb of the ray flower of compositae. 

 node place on a stem where leaves or buds 



occur. 

 ocreae a tabular stipule, or a pair of stipules, 



joined and elongated. 

 panicle a loose irregular compound flower 



cluster with flowers on small stems. 

 pappus appendages in tufts at top of ovary or 



fruit of such plants as thistle and dandelion. 



Usually cottony and useful in the dispersal of 



the fruits or seeds. 

 pedicel the stem of a single flower in a cluster. 

 peduncle the stem of a single flower. 

 petiole the stem of a leaf. 

 pome a fleshy fruit like an apple. 

 piibescent covered with short, soft hairs. 

 raceme a flower cluster of stemmed flowers on 



an elongated axis. 

 rachis the axis of a compound leaf. 

 rhizome a prostrate, subterranean stem, root- 

 ing at nodes. 

 r'ugose wrinkled. 

 scabrous rough to the touch. 

 scape a naked flower stem rising from the 



ground. 

 sej)al a leaf like outer division of the flower, 



often green. 

 sessile without an individual stem, as a leaf 



attached directly to main stem. 

 setaceous bristle shaped. 



silique a specialized capsule in which a parti- 

 tion separates each seed cavity; characteristic 



of Cruciferae. 

 spike an elongated flower axis in which the 



flowers are sessile or almost sessile. 

 stipule an appendage at the base of the petiole 



or leaf or at each side of the attachment to 



the main stem (see Fig. 6, 7). 

 terete cylindrical, having a circular cross sec- 

 tion. 

 umbel a flower cluster in which the individual 



flower stems arise from the same level (Flower 



of Wild Carrot). 

 veins the conducting tissue in a leaf. 

 villous bearing long and soft hairs. 

 rvhorl three or more leaves in a circle around 



the stem (at the node). 



