Identification Guide for Plants of Mount Desert Island

a service of
V. F. Thomas Co. - P. O. Box 55 - Bass Harbor, Maine  04653
info@vfthomas.com


(updated 19 September 2018)


Welcome to the home page of the Mount Desert Island plant identification guide.

Purpose of this guide: The purpose of this guide is to help you identify any “higher plant”, so-called, that is growing outside of cultivation on Mount Desert Island. You need to know at the outset that this will likely be a slow process; there are 831 species plus 6 hybrids in 398 genera in 112 families on Mount Desert Island. People spend many years learning to identify plants, and you should not expect that this guide will completely circumvent all that work. If you are looking for a method that promises “even a second grader can use this”, keep looking. However, if you are willing to spend some time with this guide and do the reading here that is required, you will find that you can make significant progress in learning to identify the plants of Mount Desert Island.

How to use this guide: This guide divides the plants of Mount Desert Island into seven groups, based roughly on their order of evolution. These are the same seven groups found in the tracheophyte section of the Champlain Project website. Within these groups, some families are so distinctive that they are immediately recognizable and, therefore, have their own links below to their respective family pages, which will, in turn, help you identify the plant in question. Plants in the remaining families will have to be identified using either the monilophyte table below or a multiple access key. Ultimately you will end up at a family page, and the species in question should be on that page.
   Read each description below to determine if the plant you are trying to identify belongs to one of those distinctive families or whether you will need to use either the monilophyte table or the multiple access key.



Group 1 - Lycophytes: This group of plants, along with Group 2 (Monilophytes), reproduce by spores. The remaining five groups reproduce by seeds. Finding the spores or even the seeds is not always easy, so it is probably easier to identify most of the families in these two groups by their morphology (i.e., what they look like).
   There are four families of lycophytes—two club-moss families, a quillwort family, and a spike-moss family. Read the description of each family and examine the images. If the plant you are trying to identify fits the description of one of these families, click on that family name, and you will be taken to a page that describes each species in that family. If the plant in question does not look like any of the plants shown below in these four families, move on to Group 2.

Huperziaceae: This family and the Lycopodiaceae are collectively called club-mosses. (Club-mosses are not mosses, and that is why a hyphen is placed between the two words.) All club-mosses reproduce by spores, and those spores are contained in packets called sporangia (singular: sporangium). Each sporangium is located in the angle formed by the upright stem and the upper surface of one of the tiny leaves on that stem. (There are also horizontal stems that run along the top of the ground or just below the surface, but here you need to consider only the upright stems.) The two families of club-mosses, Huperziaceae here and Lycopodiaceae below, can be differentiated by the way they bear their sporangia. In the Huperziaceae, individual sporangia are visible—you may need a hand lens—in bands around the upper part of the vertical stem. In the image below, they appear as tiny yellow dots in among the leaves a little below the top of each stem. They are visible in the plants toward the back of the image.

      Huperzia - the only genus on MDI in this family
      
      (click on image to enlarge)

Lycopodiaceae: In this family, the sporangia are not visible because each leaf under a sporangium is pressed upward against the vertical stem, thereby concealing the sporangium. The sporangia plus the leaves immediately below them constitute what is called a strobilus (plural: strobili). A strobilus is located at the very top of the vertical stem. In four of the five genera of the Lycopodiaceae (Dendrolycopodium, Diphasiastrum, Lycopodium, and Spinulum), the leaves of a strobilus are initially light green and with time become more or less straw-colored. In the other genus (Lycopodiella, fifth image below), they are the same color as the rest of the leaves, but the strobilus structure is still evident—it looks as if the tip of the stem is swollen.

      Dendrolycopodium - Here the strobilus has bent over to the left.
      
      (Click on image to enlarge)

      Diphasiastrum - [information to be added]
      
      (Click on image to enlarge)

      [Lycopodium to be added]

      Spinulum - with young strobili whose sporophylls (leaves) are still pale green. This image is of Spinulum canadense, which is not found on MDI, but it is sufficiently similar to the Spinulum species that does grow on MDI.
      
      (Click on image to enlarge)

      [Lycopodiella to be added]

Isoëtaceae: [no link yet] Quillworts are aquatic plants that are completely submerged, in just a couple feet of water all the way to {x} feet. Depending on the species, the leaves may be somewhat curled to very straight. In general, however, they are fairly similar in morphology (images to be added below) and are unlikely to be mistaken for any other group of plants.

Selaginellaceae: [no link yet] {text}
      
      (click on image to enlarge)


Group 2 - Monilophytes: There are 12 families of monilophytes on MDI. Two of them (Equisetaceae and Ophioglossaceae) are distinct enough so you can recognize them from just the images below. The remaining 10 families of monilophytes, containing a total of 25 species, can be identified by using the table below the Ophioglossaceae.

Equisetaceae: There are three species of horsetails and scouring rushes on Mount Desert Island. One species (first image below) grows in standing water and has either no branches or occasionally an odd branch or two that are somewhat stubby and make the plant look like a mutant. A second species (second image below) has both unbranched and branched stems. Its early reproductive stems are more or less flesh-colored and unbranched. These stems soon wither, yielding the way for the green, branched ones. The third species (third image below) is not only branched, but its branches are, themselves, branched.
            
      (click on an image to enlarge)

Ophioglossaceae: There are only two species of this family growing on MDI: Ophioglossum pusillum (to be added below left) and Botrychium virginianum (below right). {more text}
         
      (click on an image to enlarge)

The remaining 10 families of ferns can be determined by the following table:
leaf origin (relative to other leaves) leaf division leaf blade length leaf orientation sporangium location
Aspleniaceae solitary to a few together (mainly due to small area available) all leaflets in same plane 3–22 cm hanging (or at least protruding) from a more or less vertical crevice along veins on abaxial surface of an unmodified leaf
Blechnaceae [?] all leaflets in same plane 28–60 cm erect along veins on abaxial surface of an unmodified leaf
Dennstaedtiaceae solitary divided into three leaflets, each in a different plane or
all leaflets in same plane
15–90 cm erect under rolled over leaflet edge on abaxial surface of an otherwise unmodified leaf
Dryopteridaceae clustered, often in a “shuttlecock” all leaflets in same plane 10–80 cm erect on abaxial surface of an unmodified leaf or
on abaxial surface of a modified portion of the leaf
Onocleaceae solitary all leaflets in same plane 13–34 cm erect on a separate, highly modified leaf
Osmundaceae clustered, often in a “shuttlecock” all leaflets in same plane 20–150 cm erect on a separate, highly modified leaf or
on a highly modified portion of an otherwise unmodified leaf
Polypodiaceae solitary all leaflets in same plane 5–25 cm erect on abaxial surface of an unmodified leaf
Pteridaceae solitary to somewhat clustered all leaflets in same plane 28–80 cm erect under rolled over leaflet edge on abaxial surface of an otherwise unmodified leaf
Thelypteridaceae solitary all leaflets in same plane 4–50 cm erect on abaxial surface of an unmodified leaf or
under rolled over leaflet edge on abaxial surface of an otherwise unmodified leaf
Woodsiaceae solitary to somewhat clustered (mainly due to small area available) divided into three leaflets, each in a different plane or
all leaflets in same plane
5–80 cm erect or hanging (or at least protruding) from a more or less vertical crevice along veins on abaxial surface of an unmodified leaf


Group 3 - Nonflowering Seed Plants: The three families in this group of plants are sometimes referred to collectively as gymnosperms or conifers. The former name (gymnosperms) is sometimes enclosed in quotation marks to indicate that it is not a monophyletic group (i.e., it is not composed of all the descendants of the common ancestor of its members). The latter name (conifers) is not entirely accurate because some nonflowering seed plants do not technically have cones. What these three families (and other nonflowering seed plant families around the world) do have in common are, as the name indicates, seeds but a lack of flowers. Evolutionarily, this means that they advanced beyond spore-bearing plants through the evolution of seeds, but they did not develop flowers (and the associated fruits).
   There are three families of nonflowering seed plants: Cupressaceae, Pinaceae, and Taxaceae. They can be differentiated based on their leaves (sometimes called needles because of the shape of many of them). When you determine which family your plant belongs to, click on the name of that family.

Cupressaceae: leaves opposite (i.e., in pairs with the leaves on opposite sides of the stem from each other) and appressed to the stem (i.e., pressed against the stem, concealing it from view) or at least some leaves in whorls of three (i.e., three leaves equally spaced [=120°] around the stem) but not appressed to the stem (i.e., the stem visible). All three species are shown below.

      Juniperus communis - habit (lower left) and close-up of leaves (lower right)
         
      (click on an image to enlarge)

      Juniperus horizontalis - habit (lower left) and close-up of leaves (lower right)
         
      (click on an image to enlarge)

      Thuja occidentalis - habit (lower left) and close-up of leaves (lower right)
         
      (click on an image to enlarge)

Pinaceae: leaves alternate (i.e., attached singly to the stem but neither opposite another leaf nor in a whorl of 3) or in clusters of 2 or more originating from the same point on the stem. (images below)
            
      (click on an image to enlarge)

Taxaceae: leaves attached to the stem at some distance below the point at which they diverge from the stem, thereby making the stem appear green. (image below)
      
      (click on image to enlarge)


Group 4 - Nymphaeales: Three species of this group (botanically an order) grow on Mount Desert Island. They are members of what used to be called dicots, but those formerly named dicots actually arose evolutionarily at two different times. An early group, the Nymphaeales, evolved prior to the monocots (see below) and a later group, the Eudicots, evolved later. Because each of these groups forms a distinct lineage, it is not appropriate to lump them under the single name of “dicot”.

Nymphaeaceae:
      Brasenia schreberi (peltate leaf below right):
         
      (click on an image to enlarge)

      Nuphar variegata leaves (lower left) and flower (lower right):
         
      (click on an image to enlarge)

      Nymphaea odorata:
      
      (click on image to enlarge)


Group 5 - Monocots: The monocots represent a single evolutionary lineage, but three of the monocot families are so different from the others that they have their own links below. These are the grasses (family Poaceae), sedges (Cyperaceae), and rushes (Juncaceae), and are collectively called graminoids. They have long narrow leaves with parallel veins and lack showy flowers. Click on the appropriate family name below if the plant you are trying to identify fits one of the descriptions. The remaining monocots are combined with the Eudicots (Group 7 below) in a multiple access key. Directions for using the key are given below with Eudicots.

Poaceae: The Poaceae differ from the other graminoid families by having stems that are jointed and hollow. Their leaves are two-ranked; that is, the leaves grow in two vertical rows. Now, because grasses probably haven’t read about this feature, their leaves may not be perfectly aligned in two rows, but they will be close enough to that arrangement that you won’t confuse them with sedges, whose leaves are three-ranked.
[Add Poaceae images.]

Cyperaceae: An oft-used mnemonic device for this family is the sentence “Sedges have edges.” However, some sedges do not have edges, and there are plants with edges that aren’t sedges. But what sedges do have that distinguishes them from the other groups in this online guide are leaves in three ranks and {text}.
[Add Cyperaceae images.]

Juncaceae: Of the three graminoid families, only the rushes (Juncaceae) have flowers with petals and sepals, albeit diminutive, brown ones. Because the sepals and petals are both brown and are identical to each other except that sepals are outside the petals, they are called tepals.
[Add Juncaceae images.]

You may be able to avoid downloading and using the multiple access key if you know which monocot family the plant in question belongs to. Following is a list of the nongraminoid monocot families represented on Mount Desert Island. Click on a name to be taken directly to the web page for that family. Some distinctive features of the representatives on MDI of each family, though not necessarily exclusive to that family, are given below.

all = all MDI species in the family;
some = some MDI species in the family
aquatic/emergent leaves basal leaf blades entire tepals 6 tepals (pale) yellow miscellaneous character states
Alismataceae all all all sometimes none none
Alliaceae none all all all none inflorescence an umbel;
tepals bright pink or purple
Araceae some sometimes all sometimes all none none inflorescence a spadix
Asparagaceae none none all all none
Colchicaceae none none all all all
Eriocaulaceae all sometimes all all none none roots septate
Hydrocharitaceae all some none none none
Iridaceae none some some all none
Juncaginaceae all sometimes all all all none
Liliaceae none some all all some
Melanthiaceae none none all none none leaves 3, whorled
Orchidaceae none some all none none flowers bilaterally symmetric
Pontederiaceae all all sometimes all all none
Potamogetonaceae all none all none none
Ruppiaceae all none all none none
Ruscaceae none none all some some?
Scheuchzeriaceae all all sometimes all all sometimes
Typhaceae some some all [?] none
Xyridaceae none all sometimes all none all petals 3
Zosteraceae all (marine) none all none none


Group 6 - Ceratophyllales: It is not yet clear exactly where this plant order diverged on the tree of life, so it is listed separately from other groups. There is only one species (in one family (Ceratophyllaceae), of course) of this order on MDI. That species is shown below.

Ceratophyllaceae:
[add Ceratophyllum echinatum image(s)]


Group 7 - Eudicots: This most recently evolved lineage of plants is here combined with the nongraminoid monocots in a multiple access key. Clicking on this link will download an Excel file to your desktop or to a “Downloads” folder. If the latter, you will need to drag the file onto your desktop. After you have opened it, use Excel’s filter function by clicking on the downward pointing triangle in the cell containing the name of the character whose character states you want to filter. Because a cell may contain more than one character state (e.g., the “perianth color” for Cypripedium acaule is “pink, white”), you should filter using the “contains” option. As you filter within successive characters, you will narrow the field of possibilities to one or a few families (left hand column in the spreadsheet). Click on the name of that family (or of one of the families) to be taken to a web page for that family. You will proceed from there to identify the species in question. If the family whose name you clicked on does not contain the species in question, return to the spreadsheet. You may choose another family name, continue filtering, or perhaps reverse one or more filters if you were unsure of the various states of that character.

You may be able to avoid downloading and using the multiple access key if you know which eudicot family the plant in question belongs to. Following is a list of the eudicot families represented on Mount Desert Island. Click on a name to be taken directly to the web page for that family. Some distinctive features of the representatives on MDI of each family, though not necessarily exclusive to that family, are given below.

all = all MDI species in the family;
some = some MDI species in the family
woody leaves opposite or whorled leaves compound leaves (or leaflets of compound leaf) entire flowers bilaterally symmetric miscellaneous character states
Adoxaceae all all some one sometimes none flower petals 5, white
Amaranthaceae none one species none some none no showy flowers
Anacardiaceae all none all none none
Apiaceae some none all some none inflorescence an umbel; petals 5, white or greenish
Apocynaceae none all none all none
Aquifoliaceae all none none some sometimes none
Asteraceae none some some some [see right] disk flowers (radially symmetric) or ray flowers (bilaterally symmetric) or both disk and ray flowers on a single receptacle
Balsaminaceae none some none none all flowers with a nectary spur
Berberidaceae all none none some none armed
Betulaceae all none none none none
Boraginaceae none none none all none petals 5, (pale) blue, sympetalous
Brassicaceae none none some some sometimes none sepals 4; petals 4
Campanulaceae none none none some some sepals synsepalous; petals sympetalous
Caprifoliaceae some all one species some some
Caryophyllaceae none all none all none
Celastraceae all some none none none
Cistaceae some some none all none
Convolvulaceae none none none [?] none
Cornaceae some some none all none leaves with arcuate venation
Crassulaceae none some note some none
Droseraceae none none none all none leaves covered with gland-tipped hairs
Elatinaceae none all none all none habitat aquatic/wetlands; petal color pinkish
Ericaceae some some none some one species
Euphorbiaceae none none none all none latex milky
Fabaceae some none all but one species some all
Fagaceae all none none none none fruit acorns or beechnuts
Gentianaceae none all sometimes none all none leaves scale-like; sepals 4, synsepalous; petals 4, sympetalous
Geraniaceae none all some none none
Grossulariaceae all none none none none some armed
Haloragaceae none one species one species [?] none plants aquatic or emergent
Hamamelidaceae all none none none none leaf blade asymmetric at base; flowers in the fall
Hypericaceae one species all none all none leaves with pellucid dots (hold up to light)
Lamiaceae one species all none one species some stem with square cross section
Lentibulariaceae none some some [?] all most species aquatic; petals rose-purple (1 species) or yellow
Lythraceae some all none some none flower petals pink-purple or magenta
Malvaceae some none none [?] none
Melastomataceae none all none none all sometimes stem with square cross section; sepals 4; petals 4, magenta to pink; stamens 8, with yellow anthers
Menyanthaceae none none some all sometimes none habitat aquatic/wetland
Myrickaceae all none none none none leaves aromatic (rub them)
Myrsinaceae none all none [?] none
Oleaceae all all some some none
Onagraceae none some none some one species sepals 4; petals 4
Orobanchaceae none some none [?] all
Oxalidaceae none none all none none
Papaveraceae none none all [?] some sepals 2; petals 4
Plantaginaceae none some none [?] some
Plumbaginaceae none none none all none habitat often near saltwater; flower petals purple to lavender
Polemoniaceae none all none all none
Polygalaceae none none none all all
Polygonaceae none none none [?] none
Portulacaceae none sometimes none all none petals yellow
Ranunculaceae none one species some some none stamens many
Resedaceae none none none none all stamens many
Rhamnaceae all none none all none
Rosaceae some none some [?] none some species armed
Rubiaceae none all none none[?] none
Salicaceae all none none [at least one species] none
Sapindaceae all all none none none maple trees
Sarraceniaceae none none none [?] none leaf margins fused to form a tube (the “pitcher” of the pitcher plant)
Saxifragaceae none one species sometimes none some sometimes none
Scrophulariaceae none some none none some
Solanaceae none none none some sometimes none
Ulmaceae all none none none none elm tree; leaf blade asymmetric at the base; leaf surface feels like fine sandpaper
Urticaceae none all none none none
Verbenaceae none all none none all stem with square cross section; flower petals purple to blue
Violaceae none none none some sometimes all flowers with nectary spur
Viscaceae all all none all none parasitic on white and black spruce, sometimes on larch and white pine; leaves scale-like
Vitaceae all none all none none liana; leaves with 5 leaflets