vnevirkov 的最愛
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什麼
美洲白橡 (Quercus alba)觀察者
dziomber描述
This tree was almost in the exact spot that a white oak was noted as a witness tree on the Public Land Surveys done in the 1800's and is large enough to have been around during that time.
Approximate circumference: 127in
Approximate DBH: 40.5in
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觀察者
leenavilonen描述
Herbaceous plant about 10 inches tall. White, five parted flowers. Petals arranged in a nodding umbel. Yellow/brown at end of umbel. No fruit yet. Basal leaves that are much longer than wide.
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觀察者
alex_shure描述
practicing some sharp-shooting. Natural light, no flash 1/2000 - 1/3200sec shutter speed
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觀察者
dziomber描述
Morainal woodland
Stems prostrate or very low arching, rooting at the tips, with curved and broad-based prickles under 3mm. Leaves not tomentose abaxially, but softly pubescent with villous hairs on the veins and lamina. Petioles and inflorescences lacking glands. Infructescences not strongly ascending, mostly with 4-5 fruit condensed into a corymb with short pedicels. Primocane leaves with mostly 5 and sometimes 3 leaflets, the terminal leaflet ovate, rounded to slightly cordate and accuminate. Floricane terminal leaflets elliptical
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觀察者
dziomber描述
At the edge of a small, slightly scrubby, mesic to wet-mesic, calcareous prairie remnant that likely would have been part of a broad, marshy floodplain in the past.
Stems low-arching to trailing, with scattered broad-based prickles. Leaves abaxially with a moderate covering of soft, straight pubescence along the veins and a thinner covering on the lamina. Inflorescences eglandular, compact and cymose.
This keys out decidedly well to R. michiganensis in Flora of the Chicago Region. FOCR also mentions R. curtipes as being similar, with more rounded terminal primocane leaflets, as opposed to being cordate. The terminal primocane leaflets here (photo 5) appear to be broadly cuneate and not cordate, but they may actually be rounded since the leaflets here aren't entirely expanded.
In Vascular Flora of Illinois, this keys out well to R. curtipes if the term "velvety" is more broadly interpreted to mean softly pubescent along the veins and at least sparsely so along the lamina, more in line with the key in Flora of the Chicago Region. Another small liberty must be taken with with this key since it notes R. curtipes as having quinate primocane leaves, but other treatments also allow for ternate primocane leaves.
Interestingly, this plant keys out perfectly to R. michiganensis in Davis et al.'s 1968 treatment of R. sect. flagellares in North America. And it also keys perfectly to R. curtipes in more recent comprehensive treatments of the genus for the states of Iowa and MIssouri.
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觀察者
dziomber描述
In a drier section of Northern Flatwoods along the North Branch of the Chicago River dominated by bur and swamp white oak.
Stem and leaves basal, petals purple, spurred petal bearded, leaves sparsely pubescent, petioles hirsute. This plants keys out well to V. septentrionalis in Vascular Flora of IL, although this species isn't recognized by Flora of the Chicago Region or Flora of North America. Both of these latter floras consider V. septentrionalis to be synonymous with V. sororia. And this plant would fit V. sororia well, if not for the relatively thick beard on its spur petal and its acute, eciliate sepals.
Similar plants were seen nearby with various characteristics intermediate between V. septentrionalis and V. sororia. Other plants relatively nearby had essentially glabrous leaves and petioles and more deltate leaves like V. affinis and V. missouriensis. One plant in a nearby prairie even seemed to fit V. affinis while some other plants in a nearby floodplain seemed to fit V. missouriensis.
I'm not convinced that V. septentrionalis is entirely distinct from V. sororia, but I thought it might be useful to post this observation under that name. Some authorities suggest that V. septentrionalis may be of hybrid origin with V. sororia and V. affinis as parents. I've also seen this suggested for V. missouriensis.
