(Unadjusted P-values were only significant for four of the 240 regressions, considerably fewer than the 12 that would be expected by chance.) Single-species comparisons yielded significant correlations (adjusted for multiple comparisons) for only one of the six species examined: Ageratina altissima
, which was significantly positively correlated with A.
Pretreatment, thermoperiod and pretreatment x thermoperiod interaction had significant (P = 0.0001) effects on germination of 12-wk cold-stratified achenes of Ageratina altissima. A significant interaction indicated that the effect of pretreatment on germination was strongly dependent on the thermoperiod.
Achenes of Ageratina altissima began germinating between 14 and 20 November 1994, when mean daily maximum and minimum temperatures were 15.7 and 8.7 C, respectively [ILLUSTRATION FOR FIGURE 4 OMITTED].
Late Summer- Spring species Summer species Fall species Arisaema dracontium Circaea lutetiana Agastache nepetoides Dodecatheon meadia Cryptotaenia canadensis Ageratina altissima
Osmorhiza longistylis Galium concinnum Amphicarpaea bracteata Potentilla simplex Orbexilum onobrychis Hackelia virginiana Sanicula odorata Phytolacca americana Lactuca biennis Triosteum aurantiacum Smilax lasioneura Phryma leptostachya T.
Plants blooming later in the season include Ageratina altissima, Agrimonia spp., Campanulastrum americanum, Cryptotaenia canadensis, Sanicula odorata, Solidago caesia, Symphyotrichum cordifolium, and S.
Herbaceous plants occurring beneath these taller trees are Ageratina altissima, Cinna arundinacea, Dichanthelium clandestinum, Elymus virginicus, Galium aparine, Geum canadense, Muhlenbergia schreberi, Poa trivialis, Rubus occidentalis, Sanicula odorata, Stellaria media, Symphyotrichum lateriflorum, and Verbesina alternifolia.
Mid-summer to fall flowering forbs include Ageratina altissima
, Agrimonia pubescens, Campanulastrum americanum, Cryptotaenia canadensis, Eupatoriadelphus purpureus, Helianthus decapetalus, Heliopsis helianthoides, Polymnia canadensis, Sanicula odorata, Solidago caesia, Symphyotrichum cordifolium, and S.