SEA ARROW-GRASS

Triglochin maritima

(Formerly: Triglochin Maritimum)
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
sex
sexZbisexual

5th Aug 2009, Marshes, Lytham St Annes, Lancs. Photo: © RWD
A typical clump which grows up to 60cm high, usually a little taller than its thinner relative Marsh Arrow-grass. The leaves are grass-like but furrowed.


23rd May 2008, Salt-marshes, Shell Island, North Wales. Photo: © RWD
A typical tuft but much earlier in the year, looking like Sea Plantain (but that can have cream-coloured anthers sticking out around [some part] of the flowering spike).


5th Aug 2009, Marshes, Lytham St Annes, Lancs. Photo: © RWD
The flowers (now turned to fruits) are in long spikes, but with a slightly longer and about twice as broad a spike than those of Marsh Arrow-grass.


23rd May 2008, Salt-marshes, Shell Island, North Wales. Photo: © RWD
The broader and green barrel-shaped objects are the fruits, here with (seemingly) 4 white cross-shaped styles (Stace says that the number of styles is '±0' - giving the option of it either being minus one or maybe minus a quarter. Erm...). The browner ones here are less mature and some still have three petals plus three sepals attached.


Photo: © RWD
Here the stem is expanding increasing the distance between the fruits aka seed capsules, some of which further down have dropped off. A leaf is being held up on the right it is semicircular in cross-section with an almost flat side which is sometimes slightly concave especially lower down.
The flowers/fruits are held a little way off from the stem (unlike those of Marsh Arrow-grass which might touch the stem).


Photo: © RWD
The fruits/seed capsules (here brownish) are on shorter stalks than those of Marsh Arrow-grass. Here they are surrounded by 3 petals and 3 sepals offset by 60° from each other (but in this photo the petals are mostly hidden by the outer sepals).


5th Aug 2009, Marshes, Lytham St Annes, Lancs. Photo: © RWD
The stems are apparently ribbed, but these are the petioles of the flowers which run down the stem some way before fully merging with the stem. A long spike of flowers with only the top one-third shown. Some of the (outer) sepals have splayed outwards and downwards revealing the 3 petals still surrounding the fruits.


5th Aug 2009, Marshes, Lytham St Annes, Lancs. Photo: © RWD
The flowers have three red-tinged green sepals (here some are curled out well below the flower) and three petals also green tinged-red. The central green 'barrel' will eventually contain the seeds and is in six sections (unlike the 3 sections of Marsh Arrow-grass seeds).


Photo: © RWD
Here the ridges on the stem are in evidence - they are the stalk of the fruit running down the stem a way before fully merging with the main stem. All petals and sepals have dropped off leaving the 6-compartment seed capsule fully naked.
The flat(ish) side of the leaf is on the right with the lower half of the leaf at the bottom is beginning to be slightly concave. The half-round side is hidden on the other side.


Photo: © RWD
The half-round side of the leaf.


Photo: © RWD
The fruits of those on the left are larger and more ripe than those on the left which still have some sepals or petals attached.


Photo: © RWD


Photo: © RWD
The fruits are between 3 and 5mm long, barrel-shaped and have 6 fertile compartments. These are shorter but much wider than the 3 splayed out linear cells of Marsh Arrow-grass.


Photo: © RWD
This one with 3 sepals and 3 petals still attached. The 6 compartments are barely discernible, except from the opening at the top.


Photo: © RWD
The fruit case is minutely ridged axially.


Easily confused with : Marsh Arrow-grass, but that likes marshes rather than the salty sea water in salt-marshes. The flowers in Marsh Arrow-grass are green but edged purple and in a shorter spike than Sea Arrow-grass. However, the seeds are not long and narrow and in threes which are slightly splayed out as is Marsh Arrow-grass, but rather fat and barrel-shaped divided into SIX compartments.

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

Some similarities to : Sea Plantain which grows in similar places on sandy shores, but has a shorter flowering spike that has cream coloured anthers surrounding (at least part of) the flowering stalk.

It is Not a grass.

It is native and found near the sea all around the coastal areas of the British Isles in saltmarshes, brackish grazing marshes or grassland sprayed by sea-water after strong onshore winds. It only rarely occurs in salty places inland.

A CYANOGENIC GLYCOSIDE

It contains the toxic cyanogenic glycoside Taxiphyllin, which is similar to Lotaustralin which is found in Common Bird's-foot-Trefoil (Lotus corniculatus) and other Lotus genera plants, but with a methyl group replaced by a hydrogen atom and and extra para-phenol moiety replacing another methyl group.


  Triglochin maritima  ⇐ Global Aspect ⇒ Juncaginaceae  

Distribution
 family8Arrow-grass family8Juncaginaceae
 BSBI maps
genus8Triglochin
Triglochin
(Arrow-grasses)

SEA ARROW-GRASS

Triglochin maritima

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

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