Systematics: Originally described in 1827 as Coluber vernalis by Richard Harlan, based on specimens from "Pennsylvania and New Jersey." Schmidt (1953) restricted the type locality to the vicinity of Philadelphia; however, McCoy (1982) noted that O. vernalis does not occur in southeastern Pennsylvania. Schmidt and Necker (1936) were the first to place vernalis in the genus Opheodrys. In the Virginia literature. Hay (1902), Dunn (1918), Uhler et al. (1939), and Carroll (1950) used the name Liopeltis vernalis, following Cope (1860,1900). All other Virginia authors have used the current nomenclature.

Description: A small, slender snake reaching a maximum total length of 660 mm (26.0 inches) (Conant and Collins, 1991). In Virginia, maximum known snout-vent length (SVL) is 424 mm (16.7 inches) and maximum total length is 570 mm (22.4 inches). In the present study, tail length/total length was 25.0-36.6% (ave. = 31.5 ± 3.0, n = 43).

Scutellation: Ventrals 106-141 (ave. 128.1 ± 6.3, n = 47); subcaudals 70-91 (ave. 82.2 ± 5.5, n = 40); ventrals + subcaudals 190-222 (ave. = 211.1 ± 6.4, n = 40); all dorsal scales smooth, scale rows 15 at midbody; anal plate divided; infralabials 7/7 (24.4%, n = 41), 8/8 (29.3%%), 7/8 (22.0%), or combinations of 5-9 (23.3%); supralabials 7/7 (78.0%, n = 41%) or combinations of 6-8 (22.0%); loreal scale present; preoculars 1/1 (73.8%, n = 42) or 2/2 (26.2%); postoculars 2/2; temporal scales usually 1+2/1+2 (83.3%, n = 42) or combinations of 1-3 (16.7%).

Coloration and Pattern: Dorsum of body, tail, and head uniformly light green; venter, chin, labial scales, and rostrum uniformly yellowish green to white; green color changes to light blue in preservative.

Sexual Dimorphism: Sexual dimorphism is expressed in body size and scutellation. Adult females averaged longer (340.4 ± 39.2 mm SVL, 287-424, n = 13) than adult males (297.7 ± 23.2 mm SVL, 272-333, n = 7) and reached a longer total length (females 570 mm, males 509 mm). Sexual dimorphism index was 0.14. Average tail length/total length was higher in males (33.7 ± 1.9%, 29.6-36.6, n = 18) than females (29.8 ± 2.5%, 25.0-34.3, n = 24). Body mass was greater in adult females (ave. = 19.5 ± 5.5 g, 12-32, n = 17; males ave. = 15.3 ± 2.2 g, 12-19, n = 10).

Females possessed a slightly higher average number of ventral scales (130.6 ± 5.6,111-141, n = 26; males 124.9 ± 6.0, 106-135, n = 20), but males had a higher average number of subcaudal scales (85.2 ± 5.7, 70-91, n = 16) than females (80.1 ± 4.3, 73-90, n = 24). Counts of ventral + subcaudal scales were not sexually dimorphic (males 211.4 ± 5.1, 201-222, n = 16; females 210.9 ± 7.3,190-220, n = 24).

Juveniles: Juveniles are colored and patterned as adults, except that the green is paler. At hatching, juveniles were 88-92 mm SVL (ave. = 90.3 ± 2.1, n = 3) and 128-132 mm total length (ave. = 130.7 ± 2.3), and weighed an average of 1.1 g.

Confusing Species: Opheodrys vernalis may be confused with Rough Greensnakes (O. aestivus), which are larger and have keeled dorsal scales.

Geographic Variation: There were no differences in scutellation between samples from the Blue Ridge Mountains (BRM) and those from the Ridge and Valley (R&V) physiographic regions in Virginia, as reflected in the following counts: ventrals (BRM 129.3 ± 5.4,123- 141, n = 13; R&V 127.6 ± 6.7, 106-138, n = 34), subcaudals (BRM 81.0 ± 4.2, 78-90, n = 8; R&V 82.4 ± 5.7, 70-91, n = 32), and ventrals + subcaudals (BRM 211.9 ± 4.2, 207-219, n = 8; R&V 210.9 ± 6.9, 198-222, n = 32). Grobman (1941) demonstrated that the average number of subcaudals increased from lows in northern populations to highs in the southern populations. Although this sample included no Virginia specimens, his average value for southern males (86.5) was similar to that reported here (85.2). His value for southern females (75.7) was lower than that for Virginia females (80.1).

Biology: Little is known of the biology of O. vernalis in Virginia. Uhler et al. (1939) noted it was "restricted chiefly to open areas where it glides through the grass and bushes." I have not found it outside of high-elevation grassy fields and balds, but W. H. Martin (pers. comm.) found several road kills in southern Shenandoah National Park where the vegetative communities are open, mixed- hardwood forests. Opheodrys vernalis is well concealed in grassy areas, but individuals are occasionally found under surface objects, and some are found as road kills. Its activity season is doubtless limited by upper-elevation temperatures and weather. Museum records indicate that it has been found as early as 12 April and as late as 19 October. Linzey and Clifford (1981) noted that this species may aggregate during winter, sometimes in ant mounds.

Uhler et al. (1939) found the following prey types in five specimens: butterfly and moth larvae, fly larva, ants (perhaps secondarily ingested), wolf spiders, land snails, and an unidentified orthopteran. Prey are swallowed alive. Actual predators are unknown, but Linzey and Clifford (1981) and Ernst and Barbour (1989b) suggested domestic chickens, hawks (Buteo spp.), opossums (Didelphis virginiana), skunks (Mephitis, Spilogale), and kingsnakes and milk snakes (Lampropeltis spp.). Neill (1948b) reported that one O. vernalis specimen of unknown origin had been killed by a black widow spider (Latrodectus mactans).

Opheodrys vernalis is oviparous and lays small clutches of smooth eggs under rocks in loose loamy soil. Mating occurs in spring (usually May) and August (Fitch, 1970; Ernst and Barbour, 1989b). The smallest mature female was 287 mm SVL and the smallest male was 272 mm SVL. Clutch size for Virginia females was 2-7 eggs (ave. = 4.3 ± 2.2, n = 4). Ernst and Barbour (1989b) stated that individual clutch size was 3-13. Eggs from Virginia averaged 27.1 ± 1.9 x 9.6 ± 0.5 mm in size (length 25.8-29.3, width 9.0-10.0, n = 3) and weighed an average of 1.5 g. The single egg-laying date known is 17 July. These eggs hatched on 31 July after an incubation period of 14 days. Fitch (1970) listed average clutch sizes of 5.8-7.2 from throughout the range of this snake, egg-laying dates between 24 June and 31 July, and hatching dates in August and early September.

The population ecology of this species is unknown. Uhler et al. (1939) listed 8 specimens among the 885 they examined from the George Washington National Forest. Of 545 snakes recorded by Martin (1976) on the Blue Ridge Parkway and Skyline Drive, 14 were O. vernalis. Opheodrys vernalis does not bite nor discharge musk. It will attempt to escape predators by seeking grass cover and the safety of surface objects. It is not as arboreal as O. aestivus.

Remarks: Other common names for this species in Virginia are grass snake and garden snake (Linzey and Clifford, 1981).

Opheodrys vernalis has had a long and convoluted taxonomic history (Schmidt and Necker, 1936). Recently, Oldham and Smith (1991) compared several aspects of the biology of O. vernalis and O. aestivus and concluded that vernalis should be included in its own genus, Liochlorophis. Given that Liochlorophis (Oldham and Smith, 1991, Bull. Maryland Herpetol. Soc. 27: 201–215) is the monotypic sister genus to the monotypic genus Opheodrys, recognition of the former taxon is unnecessary, and reduces the amount of information conveyed by the names. As such, we retain vernalis in Opheodrys. The several subspecies described by Grobman (1941, Misc. Pub. Mus. Zool. Univ. Michigan 50: 1–38; 1992, J. Herpetol. 26: 176–186) are based on character clines and not currently recognized.

Conservation and Management: The apparent limitation of this snake to upper-elevation grassy habitats, especially balds, should cause some concern. The origin of these balds is not well understood and somewhat disputed. Many are being encroached around their margins by invading woody plants. If these balds and grassy areas are allowed to succeed to shrub or tree dominant communities, then the habitat may become less suitable for O. vernalis. Of primary importance to the future of this species in Virginia is information on the distribution of balds and their status, as well as reports of all information on this snake. Management practices should include active maintenance of existing balds and upper-elevation grassy areas in the range of O. vernalis.

U.S. Range