page_title: Butyriboletus regius
section_title: Description
hierarchical_section_title: Butyriboletus regius / Description
caption_attribution_description: Boletus regius sensu Thiers Location: China Camp State Park, Marin Co., California, USA Observation Notes: Thanks Dimitar, for commenting on these Mushrooms, I am drying the boletes, in one spot of the park, these pops,It&#8217;s a BIG park, I have collected them going back 9 years, &#8230; I put them in my Food Dehydrator, then in a glass jar., I have NOT eaten them..ken.. For more information about this, see the observation page at Mushroom Observer. English&#160;|&#160;español&#160;|&#160;français&#160;|&#160;italiano&#160;|&#160;македонски&#160;|&#160;português&#160;| +/−
context_page_description: Butyriboletus regius, commonly known as the royal bolete or red-capped butter bolete, is a basidiomycete fungus of the genus Boletus found in China and Europe. B. regius has a pink cap, yellow flesh, and a reticulate pattern on the stem. Harry D. Thiers described a similar mushroom from California as B. regius, though it is not the same species. B. regius in Europe does not stain when exposed to air, or stains weakly, but the California species stains blue. Both European and California species are considered choice edibles.
context_section_description: The fruit bodies of Butyriboletus regius have caps that are initially convex before flattening out in maturity, reaching a diameter of 7–20 cm (2.8–7.9 in) wide. The cap surface is pink to red, occasionally with hints of yellow or brown, more so around the margin. Initially velvety to slightly tomentose (hairy) when young, these minute hairs tend to slough off with age, and the cap develops wrinkles and pits. The cap flesh is yellow, and slowly and erratically bruises blue in North American specimens. The pores on the underside of the cap are angular, and measure about 1–2 per millimetre. The color of the pore surface is bright yellow to start, but eventually darkens somewhat, and will stain blue with damage. The depth of the tubes comprising the pores extends to 0.8–2.5 cm (0.3–1.0 in).
  The stem measures 5–13 cm (2.0–5.1 in) long by 2.5–5 cm (1.0–2.0 in) thick, and typically has a thick, bulbous base. It is solid (i.e., not hollow), and a bright yellow color, often with reddish tones, particularly near the base of the stem. The stem surface can be covered with fine yellow reticulations either throughout its length, or just on the upper portion. Butyriboletus regius produces an olive-brown spore print. Its smooth, hyaline (translucent) spores are roughly elliptical to somewhat fusoid (wider in the middle and tapering toward the ends) to more or less cylindrical, and have dimensions of 12–17 by 4–5 μm.
  Chemical tests can be used to help identify Butyriboletus regius in the field. The cap cuticle will stain a pale purple color if FeSO₄ is applied; this same test will turn the flesh grayish.
caption: Boletus regius sensu Thiers, collected in California
exif: {"Image ImageDescription": "", "Image Make": "NIKON", "Image Model": "COOLPIX L18", "Image Orientation": "Horizontal (normal)", "Image XResolution": "300", "Image YResolution": "300", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop 7.0", "Image DateTime": "2008:12:08 17:13:35", "Image YCbCrPositioning": "Co-sited", "Image ExifOffset": "232", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "842", "Thumbnail JPEGInterchangeFormatLength": "16360", "EXIF ExposureTime": "1/125", "EXIF FNumber": "39/10", "EXIF ExposureProgram": "Program Normal", "EXIF ISOSpeedRatings": "200", "EXIF ExifVersion": "0220", "EXIF DateTimeOriginal": "2008:12:07 20:51:41", "EXIF DateTimeDigitized": "2008:12:07 20:51:41", "EXIF ComponentsConfiguration": "YCbCr", "EXIF CompressedBitsPerPixel": "4", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "3", "EXIF MeteringMode": "Pattern", "EXIF LightSource": "Unknown", "EXIF Flash": "Flash fired, auto mode", "EXIF FocalLength": "12299/1000", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "3264", "EXIF ExifImageLength": "2448", "EXIF FileSource": "Digital Camera", "EXIF SceneType": "Directly Photographed", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Auto", "EXIF DigitalZoomRatio": "0", "EXIF FocalLengthIn35mmFilm": "76", "EXIF SceneCaptureType": "Standard", "EXIF GainControl": "Low gain up", "EXIF Contrast": "Normal", "EXIF Saturation": "Hard", "EXIF Sharpness": "Normal", "EXIF SubjectDistanceRange": "0"}