Willows of Massachusetts

In Massachusetts this is the only representative of the primitive section Humboldtianae, which is sometimes moved from subg. Salix to subg. Protitea Kimura (Ohashi 2001, Argus 2007). Members of the latter subgenus are broadly distributed in tropical and subtropical regions of the New and Old World. S. nigra is the only willow in Massachusetts whose bud scales have distinct overlapping margins on the adaxial side (in the rest of the species bud scales are connate). As the buds are tiny, one would need a lens in order to use this character. Among the native willows, it is one of the most common and readily recognizable species.

Images from Massachusetts plant gallery: [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21]

For centuries this willow, known as Babylon weeping willow, has been favored for cultivation around the world. The name is rather deceptive, since the species actually originates from arid and semiarid regions of China. Salix babylonica L. was introduced to Europe from the Near East, supposedly in 17th century. From Europe it was exported to North America. Though it is naturalized in the southeastern US, all New-England records are based on cultivated specimens or hybrids: S. x pendulina (S. babylonica x S. fragilis) and S. x sepulcralis (S. alba x S. babylonica). According to Argus (2007), pure S. babylonica is not found anywhere north of Maryland and West Virginia. Therefore, S. babylonica is to be excluded from New-England checklists.

Images from Massachusetts plant gallery: [1] [2] [3] [4] [5] [6]

Pure S. alba is known to be introduced to Massachusetts, but most findings appear to refer to its hybrids with the preceding and following species.

Images from Massachusetts plant gallery: [1] [2] [3] [4] [5] [6] [7] [8]

Crack willow originates from Asia Minor and Transcaucasia and was introduced to Europe during the Middle Ages. In Western Europe it has been hybridizing with S. alba to such a great extent that S. alba has lost its characteristic features (Skvortsov 1999). Pure S. fragilis is comparatively rare in Europe. Most records of this species should be attributed to hybrids (Skvortsov 1999). Perhaps the same is true for North America: most specimens named S. alba are actually S. x rubens (S. alba x fragilis). S. fragilis has been frequently considered invasive; however, this ability also has to be attributed to its hybrids. We have seen old trees in the floodplains of the Charles and Neponset. A translation of Skvortsov's article at this site is intended to help distinguish pure white as well as pure crack willow.

Images from Massachusetts plant gallery: [1] [2] [3] [4] [5] [6] [7] [8]

Introduced from Europe. Since this species cannot be easily propagated from cuttings, its naturalization in the US is hardly possible. At least some of the records might be attributed to misidentifications.

Shrubs or trees up to 6 m tall, characterized by rather large, broad, dark green shiny leaves with prominent stipules. Commonly grow on shores of lakes, river banks, and in wet meadows. According to herbarium material, should be broadly distributed in Massachusetts, though so far I never found any around Boston.

Images from other sites: [1]

Salix interior (=S. exigua subsp. interior Rowlee) has a huge distributional range in North America, its eastern limit in New England [see map]. So far I've seen it only in NY State and around Ottawa (introduced).

Usually low shrubs (up to 1.5 m tall). A rather northern plant growing on bogs and fens. Around Boston it is rare or maybe even disappearing under the pressure of invasive plants, such as Phragmites australis or Lythrum salicaria. So far I have seen it only in Canada.

Images from other sites: [1] [2] [3]

Not found in New England. Historic record (Barnstable) based on misidentification. Within the US mostly distributed around the Great Lakes, with some additional isolated locations in Canada.

Images from other sites: [1] [2]

The species was not listed in Sorrie & Somers (1999). It is known from Maine (where it is endangered), but according to Argus (2005, 2007), it may also occur in Massachusetts, New Hampshire, and Vermont. The general distribution pattern is similar to that of S. cordata, though the range is broader.

Images from other sites: [1] [2] [3]

One of the most common native willows around Boston. It is easily distinguishable, though its narrow leaves in some herbarium specimens might look similar to leaves of S. nigra.

Images from Massachusetts plant gallery: [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18]

This European willow is not listed by Sorrie & Somers (1999); however, Argus (2005, 2007) shows this species for Pennsylvania and Massachusetts. A possibility of its naturalization in North America is questionable. Most of existing records appear to refer to old and/or cultivated specimens. All herbarium samples from Massachusetts identified as S. aurita, I've seen so far, to my mind belong to S. atrocinerea or, even more likely, to hybrids S. atrocinerea x S. bebbiana.

Eurasian willow. The situation with this willow in North America is not yet clear to me. This name is frequently used in horticultural literature for "pussy willow", which can hardly be true, since S. caprea, as opposed to other Vetrix willows, is very difficult to propagate. These willows should be mostly considered Salix cinerea (as stated by G. Argus). However, some cultivated specimens that I have observed (e.g., in Ottawa) did not look like S. cinerea, either. My first assumption was that it could be a closely related species, S. aegyptiaca L. There is a noteworthy remark by A. Skvortsov (1999) about the latter: it is favored for cultivation, since it is easily propagated from cuttings, unlike S. caprea. Otherwise, one might suspect some old selections including synthetic hybrids.

I prefer to treat S. cinerea and S. atrocinerea as different species, rather than subspecies. In eastern Massachusetts S. cinerea appears to be more rare than S. atrocinerea. A. Skvortsov once told me that he had seen a typical S. cinerea on a pond shore north of Boston. The first willow I identified as S. cinerea in Massachussets, I found at the shore of Mary Dunn Pond on Cape Cod (BA). See more on distinguishing between the two closely related species.

Images from Massachusetts plant gallery: [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11]

Native to Subatlantic Europe. Highly invasive, though overlooked for a long time being confused with native willows. The species has been very frequently treated as a subspecies of Eurasian S. cinerea. Perhaps the latter could be invasive as well.
See more:

• [1] Our own article about this willow with a town distribution map
• [2] Another article
• [3] Dot distribution map in eastern Massachusetts (examined populations or those worthy of examining) with links to photos
• [4] Salix atrocinerea: identification in winter
• [5] Salix atrocinerea invading the Blue Hills Reservoir. Friends of the Blue Hills Newsletter
• [6] Comparison of Salix atrocinerea and S. cinerea

Other external links: [1], [2] (PDF or MSWord version), [3], [4] (all entries refer to October 2005.)

Images from Massachusetts plant gallery: [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27]

Shrubs up to 6 m tall. Usually this species can be easily separated from related species by its leaves, which are rather broad, flat above, with inconspicious reticulation beneath. Buds large; catkins large and dense, appearing before leaves. Rather common around Boston in wet places. We have seen it at the bottom of a rather dry hill slope, too.

Images from Massachusetts plant gallery: [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28]

According to literature and herbarium material, S. humilis, together with S. tristis (S. humilis var. tristis) should be one of the most common and broadly distributed willows in eastern Massachusetts. However, I have been looking for this species for years and as of now found very few specimens in eastern Massachusetts, though it seems to be rather common in central MA.

Images from Massachusetts plant gallery: [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33]

Most authors consider this tiny willow to be a variety of Salix humilis. However, the specimens I saw looked so different from S. humilis that I am inclined to agree with Skvortsov's opinion that these are two distinct species. See the note to the preceding species.

Images from Massachusetts plant gallery: [1] [2] [3] [4] [5] [6] [7] [8]

This willow is nearly circumboreal. It is distributed across the entire North America and Siberia, reaching the north of Scandinavia. In more southern parts of Europe, it is replaced by Salix starkeana, and both these willows could be treated as subspecies of a single species. S. bebbiana should be quite common throughout Massachusetts. However, particularly in Massachusetts, it has been frequently confused with S. atrocinerea and we don't exclude a possibility of their hybridization. We only found pure S. bebbiana in central and western MA and New Hampshire. The most striking feature of S. bebbiana, which readily separates it from any other willow in New England, can be observed in female specimens at the end of the flowering season: the catkins become very loose, their stipes considerably elongating, bracts light-colored: [1] [2] [3] The species should also be easily differentiated from S. atrocinerea by the bud shape: floriferous buds aren't very different from vegetative. Argus (2005) has even classified S. bebbiana bud gradation with the 'alba-type' (that is, the type similar to that of S. alba, see Skvortsov, 1999: 49, Fig. 2). The buds are much more flattened and elongated than those of S. discolor, as well as S. atrocinerea, S. cinerea, S. caprea, or S. aurita. The ridges under the bark in S. bebbiana not well developed or missing. In the field most specimens of S. bebbiana (unless too young) can also be easily separated from any other willows by their peculiar bark: [1] [2] [3] [4]

Images from Massachusetts plant gallery: [1] [2] [3] [4] [5] [6] [7] [8] [9]

Images from other sites: [1]

An Eurasian species. I have not seen it in nature around Boston, though twice (PL & BA) observed its putative hybrids that escaped from cultivation.

This is a species introduced from Cental Europe. The only specimen in Massachusetts we saw so far is that on the Arnold Arboretum grounds.

Not infrequent around Boston, particularly in the floodplains of the Charles and Neponset.

Images from Massachusetts plant gallery: [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20]

Usually grows in the same habitats as S. petiolaris.

Images from Massachusetts plant gallery: [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17]

A European species introduced to Massachusetts (Argus 2007).

A European species that is frequently cultivated. I have not yet seen it in nature.