MARSH ARROW-GRASS

Triglochin palustris

(Formerly: Triglochin palustre)
Arrow-grass Family [Juncaginaceae]  

month8may month8jun month8june month8jul month8july month8aug

category
category8Grasses
status
statusZnative
flower
flower8bicolour
 
flower
flower8green
 
inner
inner8purple
 
morph
morph8actino
 
petals
petalsZ3
 
type
typeZspiked
 
stem
stem8round
 
smell
smell8sweet
sweet
sex
sexZbisexual
 

23rd July 2016, Green Beach, Ainsdale, Sefton Coast. Photo: © RWD
Stems thinner than those of Sea Arrowgrass (about half as thick). As the stems grow longer the distance between flowers increases. The flower stalks are so angled as to hold the flower outwards so that it does not touch the stem (unlike the flowers of Sea Arrow-grass where the flowers do touch the stem).


23rd July 2016, Green Beach, Ainsdale, Sefton Coast. Photo: © RWD
The flower stalks are longer than those of Sea Arrow-grass. The styles form a dense white head at the top (but they do the same on Sea Arrow-grass). However, on Marsh Arrowgrass, there are 3 prongs extending upon which the flowers sit, which differs from the broader fruit with 6 parts upon which the flowers of Sea Arrow-grass sit.


26th Aug 2016, Freshfield dunes, Sefton Coast. Photo: © RWD
The styles are translucent.


26th Aug 2016, Freshfield dunes, Sefton Coast. Photo: © RWD
Eventually the styles mostly drop off the extending 3-compartmented fruit. Flower stalk long. The fruit is surrounded at the bottom by 3 sepals and 3 sepals cups which are below them and offset by 60° from them.


23rd July 2016, Green Beach, Ainsdale, Sefton Coast. Photo: © RWD
The fruit continues to extend and the 3 sepal cups drop lower. Unlike Sea Arrow-grass which has many shallow flutes on the stem, the stems of Marsh Arrowgrass are very nearly round (and half as thin). Also, the flowers on Sea Arrowgrass are much closer together and clustered around the stem.


26th Aug 2016, Freshfield dunes, Sefton Coast. Photo: © RWD
The sepals and sepal cups drop off the 3 long upright fruits (actually carpels) revealing the long and naked fruits (aka carpels).


26th Aug 2016, Freshfield dunes, Sefton Coast. Photo: © RWD
The carpels in close-up (the stem of the plant is a darker green).


26th Aug 2016, Freshfield dunes, Sefton Coast. Photo: © RWD
The fruits then start to turn upside-down (as in the one near the top). The lowest one has already turned fully upside down.


26th Aug 2016, Freshfield dunes, Sefton Coast. Photo: © RWD
The carpels turn brown (but in these specimens are still standing vertically upwards from their (now brown) flower stalks. The upside-down carpels hanging downwards from their stalks


26th Aug 2016, Freshfield dunes, Sefton Coast. Photo: © RWD
Here the 3 upside-down carpels which are hanging downwards from their stalks have started to splay apart at the bottom. These carpels are 7 to 10mm long and contain the seeds for the next generation. [A brown stem droops downwards with some presumed unfertilized flowers which are now brown - these never developed carpels].


Some similarities to : Sea Arrow-grass (triglochin maritima)

Slight resemblance to : Nothing else!

Uniquely identifiable characteristics

Distinguishing Feature :

No relation to : Arrowhead [a plant with similar name]

It is not a grass!

The leaves are not as broad as those of Sea Arrow-grass. Although the leaves are half-cylindrical in cross-section on both species - on Marsh Arrowgrass they are deeply furrowed on the flat upper side towards the base. At only 15 to 40cm tall, Marsh Arrowgrass is shorter than the 50cm of Sea Arrowgrass. Marsh Arrowgrass also smells sweet (when crushed) whereas Sea Arrow-grass hardly smells.


  Triglochin palustris  ⇐ Global Aspect ⇒ Juncaginaceae  

Distribution
 family8Arrow-grass family8Juncaginaceae
 BSBI maps
genus8Triglochin
Triglochin
(Arrowgrasses)

MARSH ARROW-GRASS

Triglochin palustris

(Formerly: Triglochin palustre)
Arrow-grass Family [Juncaginaceae]  

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