1 April
Carpinus caroliniana, musclewood, blue-beech; understory tree in rich woods (1999).
Berteroa incana, hoary alyssum; alien, invasive, in fields (2010; previously 30 April 1977).
Salix discolor, pussy willow; native small tree in wet areas (2010; previously 5 April 1973).

2 April
Acer negundo, box elder; tree, open woodlands, weedy (Ron Tschida, 2010; 4 April Emmet, 2010; previously 12 April 1987).
Geum triflorum, prairie-smoke; dry prairies (2010; previously 27 April 1981).
Sanguinaria canadensis, bloodroot; woods (2010; previously 13 April 1985).

3 April
Pachysandra terminalis, garden flower (2010, Alvin Bogdansky).
Tulipa sp., tulip; garden flower (2010).

4 April
Glechoma hederacea, creeping-charlie; alien, invasive in moist semi-shaded areas (2010; previously 12 April 1987).
Antennaria neglecta, narrow-leaved pussytoes; open areas (2010; previously 20 April 1986).
Muscari botryoides, grape-hyacinth; garden flower (2010).
Erysimum cheiranthoides, wormseed mustard; alien, open areas (2010).
Veronica arvensis, field speedwell; alien, open areas (2010; previously 28 April 1998).
Chionodoxa luciliae, glory-of-the-snows; garden flower (2010)
Magnolia stellata, star magnolia; cultivated tree, alien (2010).
Anemone (Hepatica) americana, blunt-lobed hepatica; rich woods (2010; previously 5 April 1998).
Claytonia virginica, spring beauty; rich woods (2010; previously 11 April 1998).

5 April
Chamaedaphne calyculata, leatherleaf; shrub in bogs (2010; previously 19 April 1986).
Bergenia sp., garden flower (2010).
Descurainia pinnata, tansy mustard, alien weed (2010).
Prunus tomentosa, Nanking cherry, cultivated small tree (2010).

6 April
Ribes triste, swamp currant; conifer swamps (2010; previously 20 April 1985).

7 April
Dicentra spectabilis, bleeding heart, cultivated garden flower (2010).
Shepherdia argentea, buffalo-berry; alien here, spreading slightly (1986).
Rhododendron 'PJM'; cultivated shrub (1991; in 2010 on 12 April).

8 April
Cornus mas, Cornelian cherry, cultivated shrub (2010).
Chaenomeles japonica, flowering quince, cultivated shrub (2010).

9 April
Iris sp., garden flower (2010)
Luzula acuminata, wood rush; open woods (2010, 1991).

10 April
Acer platanoides, Norway maple; cultivated alien tree (2010).
Carex pensylvanica, Pennsylvania sedge; open woods (2010, previously 11 April 1987).
Dicentra cucullaria, Dutchman's breeches; rich woods (2010; previously 16 April 1988).
Mertensia virginica, Virginia bluebells; garden flower (2010).
Viola tricolor, pansy; garden flower (2010).

11 April
Asarum canadense, wild ginger; rich woods (2010; previously 17 April 1977, 1999).
Barbarea vulgaris, yellow rocket; alien and agressive in fields (2010 at Powers Bluff (A. Bogdansky); previously 24 April 1988).
Caltha palustris, marsh marigold; swamps and semi-open wetlands (2010 near Powers Bluff, A. Bogdansky; 20 April 1985).
Carex pedunculata, long-stalked sedge; rich woods (1987).
Consolida ajacis, knight’s spur; garden flower (2010).
Enemion (Isopyrum) biternatum, false rue-anemone; rich woods (2010; previously 18 April 1992).
Sibbaldiopsis (Potentilla) tridentata, three-toothed cinquefoil, native herb (2010).

13 April
Betula papyrifera, paper birch; woods and cultivated (2010; previously 21 April 1977).
Malus cf coronaria sp., cultivated apple tree (2010).
Populus grandidentata, big-toothed aspen, native tree (2010).

14 April
Vinca minor, creeping periwinkle; alien and becoming invasive in woodlands (2010; previously 23 April 1987).
Phlox sp., garden phlox; cultivated herb (2010).

15 April
Anemone quinquefolia, wood anemone; rich woods (2010, Tracy Feldman; previously 17 April 1999).
Betula nigra, river birch; tree on floodplain woods and cultivated (2010; previously 25 April 1977).
Oryzopsis asperifolia, rough-leaved rice-grass, native herb (2010 by Noela Martell-Segura; previously 23 April 1976).
Rumex acetosella, sheep sorrel; alien weed (2010).
Thalictrum dioicum, early rue; rich woods (2010; previously 28 April 1987).

16 April
Carex sprengelii, Sprengel’s sedge; native woodland herb (2010).
Trillium grandiflorum, large-flowered trillium; rich woods (1988; 17 April 2010).

17 April
Amelanchier leavis, downy juneberry, native small tree (2010; previously 30 April 2000).
Arabis lyrata, sand cress; open sandy areas (2010; previously 24 April 1998).
Epigaea repens, trailing arbutus; open coniferous woodlands (1976).
Chrysosplenium americanum, golden-saxifrage; springy seepages (1983).
Vaccinium angustifolium, early blueberry; sandy fields and woodlands (2010; previously 25 April 1977).

18 April
Erythronium albidum, white trout-lily; rich woods (2010 in Wood Co., A. Bogdansky;  previously 21 April 1987).
Erythronium americanum, yellow trout-lily; rich woods (2010 in Wood Co., A. Bogdansky; previously 27 April 1986).
Euphorbia cyparissias, graveyard spurge; alien weed (2010).
Cardamine concatenata (Dentaria laciniata), cut-leaved toothwort; rich woods (2010; previously 26 April 1985).
Carex umbellata, hidden-seeded sedge; open sand (2010; previously 20 April 1977).
Myosotis scorpioides, forget-me-not; alien weed (2010).
Pulmonaria officinalis, lungwort; garden flower (N. Martell-Segura, 2010).

19 April
Primula veris, English primrose; garden flower (2010).
Thalictrum (Anemonella) thalictroides, rue-anemone; rich woods (2010; previously 29 April 1989).
Viola blanda, sweet white violet; cool moist woods (1976 and 2010).
Viola labradorica (V. conspersa), dog violet; woodlands (2010; previously 27 April 1986).
Viola mackloskeyi (V. pallens), small white violet; cool moist woods (2010; previously 28 April 1973).
Viola pubescens, downy yellow violet; rich woods (2010; previously 25 April 1985).

20 April
Arctostaphylos uva-ursi, bearberry; open sandy areas (1973).
Cercis canadensis, redbud; cultivated alien tree (2010).
Ostrya virginiana, ironwood; tree in rich woods (2010; previously 30 April 1977).
Coptis trifolia, gold-thread; cool rich woods (1987; 24 April 2010, M. Bartkowiak).
Panax trifolius, dwarf ginseng; rich woods (2010 by T. Feldman; previously 25 April 1998).
Sambucus racemosa (S. pubens), red elderberry; shrub at edge of woods (2010; previously 28 April 1986).
Uvularia sessilifolia, sessile-leaved bellwort; rich woods (2010 by T. Feldman ; 1987).

21 April
Fraxinus pennsylvanica, green ash; tree in moist woods and cultivated (2010; previously 30 April 1985).
Uvularia grandiflora, large-flowered bellwort; rich woods (1987).

22 April
Aquilegia canadensis, columbine; native herb (2010).
Convallaria majalis, lily-of-the-valley; garden flower, sometimes spreading (2010).

23 April
Cardamine douglassii, purple spring-cress; springy seepages.
Comptonia peregrina, sweetfern; sandy woodlands and fields (2010; previously 25 April 1985).

24 April
Caulophyllum thalictroides, blue cohosh, native woodland herb (2010).
Fragaria virginiana, wild strawberry; fields and open woodlands (2010 by R. Kohlmoss; previously, 28 April 1973).

25 April
Aesculus hippocastanum., horse chestnut, alien cultivated tree (2010).
Baptisia australis, blue-flowered wild indigo, cultivated garden flower (2010).
Lonicera tartarica, Tartarian honeysuckle; alien invasive shrub (2010).
Syringa vulgaris, common lilac, cultivated shrub (2010).

26 April
Veronica peregrina, wandering speedwell; alien weed (2010). 
Ribes missouriense, Missouri gooseberry; woodlands (1977).
Zanthoxylum americanum, prickly-ash; invasive, grazed woodlands and thickets (1977).
Ribes americanum, American black currant; woodlands (1985, 2010).
Viola pedata, bird's-foot violet; sandy woodlands and dry prairies (1998; 30 April in 2010).
Viola adunca, sand violet; sandy woodlands (1981).
Arisaema triphyllum, jack-in-the-pulpit; rich woods (1998).
Ranunculus abortivus, kidney-leaved buttercup; moist woodlands (1985).

27 April
Lonicera canadensis, Canadian honeysuckle; shrub in rich woods (1986; 24 April 2010 in Oconto Co.).

28 April
Viola sagittata, arrowleaved violet; sandy fields (1987).
Mitella diphylla, bishop's-cap; rich woods (1987).
Polemonium reptans, jacob’s ladder, native woodland herb (2010).

29 April
Alliaria petiolata, garlic mustard; alien, very invasive in woods (2000).
Berberis thunbergii, Japanese barberry, alien invasive shrub (2010).

30 April
Aronia sp., chokeberry, cultivated shrub (2010).
Centaurea cyanus, batchelor buttons, cultivated garden flower (2010).
Galium verum, bedstraw, cultivated garden flower (2010).
Nepeta sp., dwarf catnip, cultivated garden flower (2010).
Silene latifolia, evening lychnis, alien weed (2010).

3 May 2010
Oxytropis campestris var. chartacea, Fassett’s locoweed (Feldman)