Lomatium cuspidatum (non-technical)


We made the AI cutoff - thanks to all who helped.

Similar in appearance (but non overlapping range/habitat): Lomatium minus, Lomatium roneorum.

Lomatium cuspidatum is of special interest because it is one of relatively few Pacific Northwest plants nearly or completely restricted to ultramafic (serpentine related) rock, a rare type of rock that derives from the earth's mantle and is a challenging substrate for most plants. Unlike many other Lomatium species, this one can be identified with a little attention even when not in flower.

1) all reports are restricted to the Wenatchee Mountains, usually or always on ultramafic (serpentine related) rock, which means mostly just south of Ingalls Creek in the north Teanaway area, with outcrops to the northwest from Lake Ingalls to Paddy-Go-Easy Pass, eastwards toward Bean and Earl Peaks, and an outcrop between Cashmere Mountain and Eightmile Mountain. Other outcrops occur around Highchair Mountain and just east of route 97 north of Blewett Pass. The high region of the Enchantments is granite, with no ultramafic outcrops.

2) plants are rather low to the ground and leaves have a blue-gray color, usually quite pronounced as the leaves mature. The plants are often so low and small that they are hard to notice, but once you see a few they are easily recognizable. They also blend into the gray-green serpentinite scree where they often occur, so keep a sharp eye out (fourth and fifth photos in https://www.inaturalist.org/observations/127153647). If you brush the leaves they have a cedary scent (personal observation). A random passerby said they smelled like Cannabis, but I didn't smell that.

3) the leaves are hairless, dissected, stubby, and fleshy, and the leaflets have a tiny sharp tip (often looks thorn-like, brown to reddish in color). The leaves are held in clusters on thick fleshy hairless branched stalks (third photo https://www.inaturalist.org/observations/133627703). The sharp extended leaf tip is diagnostic for the species (combined with location and gross appearance). The species name cuspidatum refers to this cusped leaf tip. The fourth photo on https://www.inaturalist.org/observations/121648702 shows this character and there are closeups in https://www.inaturalist.org/observations/127115955 and https://www.inaturalist.org/observations/127121648. When touched, the leaves and leaf stalks feel somewhat stiff (not at all floppy) but the sharp leaf tip won't feel like a thorn.

4) like all Lomatium species the flowers form a compound umbel (several clusters of small flowers held on a stalk, branching like the spokes of an umbrella as in photo 2 of https://www.inaturalist.org/observations/127684411). The flowers are held on thick fleshy stalks that originate at the plant base and extend well above the foliage. The flowers are brownish-purple to brownish-red and individually are very small. They appear early in the season just as new leaf growth is starting, when the leaves are not yet so blue-grey (https://www.inaturalist.org/observations/75614987). The flowering season varies a lot by place and year due to snow pack, but typically is in May to June shortly after snow melts in the particular plant's location.

The only other plant I know of that can be confused with L. cuspidatum is the (probably) much rarer Lomatium roneorum, about which relatively little is known since it is only newly recognized as a species (https://www.inaturalist.org/taxa/910740-Lomatium-roneorum). L. roneorum is not thought to be present in the southern parts of the Wenatchee Mountains, though it is present north of the Enchantments area, where it grows on the whitish chalky Chumstick formation and on acidic metamorphic rock near Basalt Peak. It has not yet been observed on serpentine. It has red-suffused yellow flowers rather than dark purple flowers, and has wider and flatter leaflets that lack the thorn-like tip, though the leaflet does come to a point.

Photos of growth stages:
Very early leafing out/flowers just opening: https://www.inaturalist.org/observations/75614987
Full bloom: https://www.inaturalist.org/observations/122600882
Late, in fruit: https://www.inaturalist.org/observations/127115955

I am keen to encourage observations of L. cuspidatum. Thus far my observations suggest it is especially abundant on steep unstable fine to mixed-sized serpentinite scree (usually not coarser talus), which is easy to recognize by its gray-green color (often mixed with a reddish weathered form) and nearly barren appearance (even on satellite images). Trails often avoid such scree because it is so unstable, so keep an eye out when the trail skirts an edge of it.

[You are welcome to improve this post by sending me an iNaturalist email, but I am disabling direct comments because this is intended as a brief guide, not a discussion.]

Publicado el 17 de julio de 2022 19:10 por jhorthos jhorthos